Introductory Entomology (ENT 201)

Introductory Entomology (ENT 201) B.Sc. Ag 3rd Sem.

1. Introductory Entomology B.Sc. Ag 3 rd Sem . Special Thanks: Lamjung Campus

2. Course Code: ENT 211 Course Title: Introductory Entomology Credit Hours: 3(2+1) Full Marks:75 Theory: 50, Practical: 25

3. Introduction - Definition, position of insects in animal kingdom

4. Definition Entomology is a branch of zoology that deals with the study of insects. The term is derived from the Greek word Entomon = Insects and logos = study . Agricultural Entomology deals with the study of insects that affect agriculture. There are other branches of entomology, such as medical entomology, veterinary entomology, forest entomology and forensic entomology (study of insects inhabiting decomposing remains).

5. Insect The world insect derived from the Latin word ‘ Insectum ’ which means ‘to cut into’. Insects, whose body is divided into three regions namely head, thorax and abdomen Having two pairs of wings and three pairs of legs in thoracic region Genital organs towards posterior end of the body and with decentralized nervous system They have open blood system, bilaterally symmetrical body and decentralized nervous system  Insects occupy 2/3rd of total population of Phylum Arthropoda

6. Characters of Class Insecta Body divided in to 3 segments: head, thorax and abdomen Possess three pairs of legs, hence the name Hexapoda Presence of one or two pairs of wings A pair of antennae Respiration by means of internal air tubes known as trachea Genital opening situated at the posterior end of the body Presence of metamorphosis (incomplete/complete) during development Possess exoskeleton made up of hard cuticle which plays important role for survival Excretion is mainly by malpighian tubules which help in maintaining ionic balance

7. The phylum Arthropoda Some characteristics of the Arthropoda are: They have a so called exoskeleton. They do not have bones, but the hard outer covering supports the muscles. The appendages are jointed. The body is formed of a number of segments. Characteristics of the class Hexapoda (Insects) Some characteristics of insects are: Body: The body is divided into three distinct regions: head, thorax and abdomen Head: One pair of antennae. The antennae are usually used as tactile organs (= organs pertaining to the sense of touch) or as olfactory organs (= organs of smell). Eyes: Most insects possess one pair of compound eyes and sometimes some simple eyes called " ocelli ". Mouthparts. There is a big variety in types of mouthparts; biting, sucking, stinging, licking, etc. Thorax: Three pairs of legs. The thorax has three segments. These are called pro-thorax, meso -thorax and meta-thorax. Each segment has one pair of legs. The different parts of the leg are called coxa , trochanter , femur, tibia, and tarsus. Note: some insects are legless, or have fewer than 6 legs. Some larvae have leg-like appendages on the abdomen. Often one or two pairs of wings. The wings are borne by the second and/or third of the thoracic segments. Note: Some insects are wingless. Abdomen: The gonopore (genital opening) is at the posterior end of the abdomen. No appendages used for moving on the abdomen of adults (except in a few primitive insects). Sometimes there are some appendages at the end of the abdomen.

8. FEATURES OF ARTHROPODS Arthropoda (from Greek words arthros = jointed, podos = foot ) is the largest phylum in the Animal Kingdom Arthropods are segmented animals which have jointed appendages. All arthropods have: All arthropods possess: Body is divided into head, thorax and abdomen. Sometimes head and thorax are united together to form cephalothorax Exoskeleton - a hard protective covering around the outside of the body (divided by sutures into plates called sclerites ) Segmented body Jointed limbs and jointed mouthparts - that allow extensive specialization Bilateral symmetry - whereby a central line can divide the body into two identical halves, left and right Nervous system is fully developed Dorsal blood pump (open blood vascular system are found).

9. Contd ….. Heart is long and contractile Alimentary canal is complete Mouthparts are present around the mouth which is used in puncturing, sucking and chewing Muscular system is well developed Excretion takes place by Malpighian tubules  The Phylum Arthropoda includes the class Insecta and other classes like the Arachnida , the Chilopoda , the Diplopoda and the Crustacea . It is with these groups that the insects, especially the wingless ones, are most likely to be confused and the main characters that are used to differentiate these classes are:

10. Systematic Classification of Insects Kingdom - Animal Phylum – Arthropoda Class – Insecta Order – Lepidoptera (Butterflies and moths) Family – Noctuidae Genus – Helicoverpa Species – armigera

11. Class: Arachnida (arachnids): spiders, scorpions, ticks, mites, etc.  Arachnids possess :   Terrestrial, 2 body segments - cephalothorax and abdomen 4 pairs of legs, simple eyes, respiration is done by gills or lungs no antennae It has 4 sub classes: Scorpinida : E.g. Scorpion Phalangida : E.g. Harvest man or Daddy long leg. Araneida ; E.g. Spiders 4. Acarina : E.g. Ticks and Mites.

12. Class: Chilopoda (Centipedes)   Chilopods are quick moving predators with poison glands which possess: Terrestrial in habitat, body is long, flattened and multi-segmented 1 pair of legs per body segment 1 pair of antennae 1st pair of legs modified into venomous “fangs” Animals are unisexual. E.g. centipedes

13. Class: Diplopoda (millipedes) Diplopods are slow moving vegetarians which possess: Many body segments, long and cylindrical 2 pair of legs per body segment 1 pair of antennae E.g.: millipedes

14. Class: Crustacea (Crustaceans): crabs, shrimp, barnacles, sow bugs, etc. Crustaceans possess: Mostly aquatic, free living parasites Two body regions – Cephalothorax and abdomen Pairs of antennae Varied number of legs (usually five) Respiration is done by skin or by gills Excretion is done by green glands Mostly unisexual.

15. Class: Insecta (Insects); beetles, bugs, wasps, moths, flies, etc. Insects possess: 3 body segments 6 legs 1 pair of antennae Most flying insects possess two pairs of wings

16. Reasons for the dominance of insects over other animals

17. Most successful group of organisms on the planet 1. NUMBER OF SPECIES Every 2 out of 3 living things is an insect Entomologists estimate that over 900,000 insects (species) have been named Plant Kingdom 400,000 species Animal Kingdom 250,000 species 2. NUMBER OF INDIVIDUALS Another way to look a the dominance of insects is to consider the distribution and density of individual species of populations Small size and high reproductive potential = population of epic proportions A migratory locusts may contain up to 10 billion individuals, cover an area of several thousand hectares, and have a total biomass of over 30,000 metric tons Grape leafhoppers reach populations as dense as 30 million hectare in some vineyards THE DOMINANCE OF INSECTS

18. A single colony of Australian termites can swell to several million individuals within an earthen mound 20-25 feet tall 3. DISTRIBUTION A third way to assess the dominance of insects is to examine their abundance and diversity in a wide range of ecological habitats Insects are found in virtually every terrestrial and fresh water environment on the face of the earth. Insect can be found in temperature varied from -20 C (Ice bug) to 80 C (locust) Contd ….

19. REASONS OF DOMINANCE Structural characters :- Exoskeleton : The insect body has an outer exoskeleton or body wall made up of cuticular protein called as chitin. This is light in weight and gives strength, rigidity and flexibility to the insect body. Prevent from desiccation or water loss Prevent from physical or mechanical injuries and to maintain shape and size of the body, providing area for muscle attachment Giving strength to the body appendages

20. Contd …. 2. Small size : Most species are of insects are between 2 and 200 mm (0.1 -1.0 inch) in length Some may be smaller while some may be bigger like Goliath beetle of Africa ( 4 inch ) and walkingstick of Malaysia (13 inch) It helps the insects to exploit different ecological niches inaccessible for other animals. Minimal resources are needed for survival and reproduction Ideal for avoiding predation

21. Contd …. 3. Flight Insects are the only invertebrates that can fly Highly effective mode of escape from predators Efficient means of transportation, allows populations to expand to new habitats and resources Efficient use of energy allows some insects to travel great distances or remain airborne for long periods of time. Monarch butterfly can fly 600 km at time.

22. Contd …. 4. Hexapod locomotion : Because of the presence of six legs on the three thoracic segments The insect will have equilibrium during all the phases of its locomotion 5. Compound eyes: Most of the adult insects and nymphs consists of compound eyes as visual organs which possess number of hexagonal units known as ommatidia . Because of presence of number of ommatidia , even if some or few ommatidia get damaged, the insect does not lose the power of vision Compound eye comprised of few to as many as 28,000 (in dragonflies) ommatidia Houseflies and dragonflies have eyes that cover most of their head. This gives them almost 360 degree vision, enabling them to see predators coming from any direction.

23. Contd …. 6. Scattered sense organs : The sense organs viz., visual organs, gustatory organs (senses of taste) , smell (olfaction), organs of touch etc. are distributed on different parts of the body Like antennae, eyes, mouth parts in the head, legs with claws on thorax, tympanum (auditory membrane), cerci ( sensory appendages) at the posterior of the abdomen etc. This scatterings on all parts of the body prevents the chance of all being damaged

24. Contd …. II. Developmental characters:- High Fecundity Egg laying capacity of a female insects. It helps to increase the population at faster rate. e.g. Queen Honey bee can produce 4000 eggs per day. 2. Method of reproduction : Many species of insects (aphids, scales, thrips , and midges) can reproduce without males- parthenogenesis Oviparous (egg laying) and viviparous (giving birth to active young) 3. Controlled reproduction : Though insects possess high fecundity, there is also high degree of control over reproduction by reducing the number of females that can lay eggs. This character is mostly seen in social insects such as honey bees and termites.

25. Contd …. 4. Short life cycle: Most of insects have very short life cycle i.e. 2 to 4 weeks Dorsophila melanogaster has shortest development time (egg to adult) is 7 days, is achieved at 28 °C Similarly, a flesh fly has a life cycle of 3 days. The adult mayflies are short-lived, from a few minutes to a few days normally say one day, depending on the species. Whose immature stage usually lasts one year in fresh water

26. Contd …. Feeds on variety of foods and Specificity of food: III. Protective adaptations and devices:- Morphological adaptations (mimicry): The body color and shape of some insects make them look like part of the plant e.g.: stick insects and leaf insects Physiological adaptations: Some insects produce or release poisonous or unpleasant odors from their body or possess warning coloration by imitating certain distasteful insects. E.g.: Stink bugs have specialized exocrine glands located in the thorax or abdomen that produce foul smelling hydrocarbons. Larvae of swallow tail butterflies have eversible glands called osmeteria , located just behind the head when disturbed they release repellent volatile and waves their body back and forth to ward of intruders Some blister beetles ( Meloidae ) produce cantharidin , a strong irritant and blistering agent

27. Contd …. Behavioral adaptations: It is a defense strategy adopted by some insects through feigning death or imitating the voice of dangerous insects or mimicry. Colarado potato beetles when disturbed, draw their legs beneath and drop to the ground and pretend as if dead. Hairy caterpillars 4. Construction of protective structures : Some insects construct shelter with the available plant material for protecting themselves from adverse conditions, natural enemies and to store food material for use during the period of scarcity Cases / Bags in case of case worms/bag worms. Termatoria in case of termites Honey comb in case of honey bees

28. If one pair of housefly is left to bred from April-August, they produce progeny enough to cover this world with 47' (feet) deep layer. Such case will happen if all the flies with remain a live and produce continuously Cicada has life of 17 years. The female member of cicada is voice less. So, there is a saying, " Happy the cicada's life because they have voiceless wife ".

29. BENEFICIAL AND HARMFUL EFFECTS OF INSECTS CHAPTER 3:

30. There are over 900,000 insects (species) have been named Of which only about 10,000 species are incriminated as pests of agriculture, forests and livestock i.e. about only 1% Rest are either beneficial or indifferent

31. Beneficial effects   Pollination - Insects such as honey bees, beetles and wasps aid in pollinating our crops and fruit trees. Crops in Rosaceae , Cucurbitaceae and Leguminosae are exclusively pollinated by bee. It is estimated that 80% of the commercial food crops are pollinated by honey bees. 2. Bio-control agents - Some parasitic and predatory insects are excellent bio-control agents for controlling other injurious insects. Example Encarsia formosa is an excellent bio-control agent for white flies on tomatoes and potatoes. 3. Production of products - Honey, wax, silk (from Bombyx mori ), shellac (from Laccifer lacca ) and cochineal (red dye widely used in cosmetics, medicinal and food products) derived from, a scale insect, Dactylopius coccus . 4. Nutrient recycling - Insects feed on dead and decaying plants, animals and animal excreta and help in recycling the nutrients. Some insects burrow into soils and improve the soil structure and texture. Examples are dung feeders dung beetles and termites. 5. Source of food - over 500 species of insects are used as food by humans -usually crickets, grasshoppers, beetle, wasp, butterfly larvae, bugs etc.

32. Contd …. 6. Insects useful as drugs, ornaments and scientific research . As medicine e.g. Sting of honey bees- remedy for rheumatism and arthritis Eanthoridin - extracted from blister beetle –useful as hair tonic Ornaments, entertainers - Artists and designers copy color of butterflies. , Beetles worm as necklace. Insect collection is a hobby Scientific research - Drosophila and mosquitoes are useful in genetic and toxicological studies respectively.

33. Detrimental effects   Destruction or spoilage of food (both fresh and stored) and crops (including forests) Crop losses due to insect pests in Nepal is about 15-20 % ( Neupane , 2058). ( In world 12.5%, Cramer, 1967) Damage to goods - leather, paper, textiles, (by beetles, cockroaches, silverfish or moths), timber (by termites and different types of borers). Transmits disease in plants and animals: Disease causing Mosquito- Malaria, Filariasis , and dengue fever. Housefly- Typhoid, Cholera, Leprosy, Anthrax Possess venoms and cause allergies Some insects are a nuisance to our well-being -house flies, ants, mosquitoes Cause phobias – fear of grisly caterpillars or spiders (arachnophobia) Require use of pesticides and other poisons, which often harm other animals

34. Body segmentation of Insect Insect have segmented bodies with certain segments fusing to form three usually well defined regions: head, thorax and abdomen. The grouping of segments into functional regions is known as tagmosis Head consists of 6 segments . Head comprises of mouthparts, compound eyes, simple eyes ( ocelli ) and a pair of antennae. Thorax consists of 3 segments i.e. prothorax , mesothorax and metathorax , Meso and metathorax are together known as pterothorax . All the three thoracic segments possess a pair of legs and meso and meta-thorax each possess one pair of wings. Abdomen has 7-11 segments with genital appendages. The 8 and 9 segments in female and 8 segment in male insects are modified to bear genital appendices.

35. Contd …. The outer parts of every segments of body is hard, colored and complex in nature. There are hard, colored and complex plates in each segments of insect body which is called sclerites . The sclerites present on dorsal side is called tergides , Lateral side is called pleurites and Ventral side is called sternites . Segments except in head (6 segments fused together to form a capsule) joint together with a flexible soft and white membrane called inter segmental membrane.

36. Insect Body wall/Integument/Exoskeleton The cuticle is the characteristic feature of arthropods and is to a large extent responsible for the success of insects as terrestrial animals. The body wall or integument is the outer layer of insect and bends inwards at various points to form supporting ridges or braces. The body wall of insect is composed of three principal layers: the cuticle, epidermis and basement membrane.

37. General structure of the insect cuticle

38. 1. Cuticle The cuticle is an outer layer which contains a characteristic chemical compounds called chitin, proteins and pigments. The cuticle is made up of three principal layers: epicuticle , exocuticle and endocuticle . The exo - and endo - cuticle together referred as procuticle .

39. Contd …. a. Epicuticle : Epicuticle is the outer, thin, delicate layer without any chitin and may have four sub- layers i . Inner epicuticle : it is the thickest layer of 0.5 to 2.0 µm immediately outside the procuticle and chemically consists of tanned lipoproteins. ii. Outer epicuticle : This is very thin trilaminar layer only of about 15 nm. It is the first formed layer of new cuticle product at each molt protecting the new procuticle from the molting enzymes. The material forming the outer epicuticle is highly polymerized lipid is often referred to as cuticulin . iii. Epicuticular wax layer : The wax layer contains many different compounds but wax comprises over 90% and is important in water proofing the cuticle. iv. Cuticular cement layer : The cement is very thin layer outside most of wax and consists of mucopolysaccharide . It protects underlying wax and not produced by all insects.

40. Contd … b. Exocuticle : It is a thicker layer below epicuticle and is often darker and harder than the rest. It contributes rigidity and toughness to the cuticle. The exocuticle is wanting or considerably reduced in the regions of integument which are more flexible. The exocuticle structurally consists mainly of chitin and protein. Chitin is a polymerized nitrogenous polysaccharide linked to protein. It is pigmented by a hard brown material as is referred to as tanned . Other constituents of cuticle include quinones which polymerized to form dark brown or black pigment known as melanin and in others quinones are utilized in forming sclerotin . c. Endocuticle : The inner undifferentiated part below the exocuticle is endocuticle and is characterized by the presence of chitin. Endoskeleton of insect cuticle provides space for attachment of muscles of antenna and mouthparts, called as Tentorium

41. Contd … 2. Epidermis: It is a cellular layer of one cell thick beneath endocuticle . The epidermal cells are glandular and secrete cuticle and the enzymes for the cuticle formation and digestion at the time of molting. Some of the epidermal cells have specialized glandular function. 3. Basement membrane: The basement membrane is also called basal lamila . It is a noncellular layer beneath epidermis and serves as stable platform where epidermal cells are anchored and muscles are attached

42. Molting Process of shedding of or casting of old cuticle or exoskeleton known as molting. Apolysis : separation of epidermis from cuticle known as apolysis . Ecdysis : shedding of the old cuticle. Sclerotization : The process of hardening involves the development of cross links between protein chains which is also known as sclerotization .

43. Insect Head Insect head is a hard and highly sclerotized compact structure. It is the foremost part in insect body consisting of 6 segments that are fused to form a head capsule. The head is connected to the thorax by a flexible neck or cervis strengthened by small cervical sclerites The head segments can be divided in to two regions i.e. procephalon and gnathocephalon (mouth).

44. Types of head or orientation of Head The orientation of head with respect to the rest of the body varies. According to the position or projection of mouth parts, the head of the insect can be classified as:  A) Hypognathous (Hypo – Below: Gnathous – Jaw) The head remain vertical and is at right angle to the long axis of the body and mouth parts are ventrally placed and projected downwards. This is also known as Orthopteroid type. Eg : Grasshopper, Cockroach  

45. Contd ….. (b) Prognathous : (Pro – infront : Gnathous – Jaw) the head remains in the same axis to body and mouth parts are projected forward. This is also known as Coleopteroid type. Eg : beetles

46. Contd … (c) Opisthognathous : ( Opistho – behind: Gnathous – Jaw) It is same as prognathous but mouthparts are directed backward and held in between the fore legs. .This is also known as Hemipteroid or Opisthorhynchous type. E. g: bugs

47. Antennae All insect except Protura possess a pair of antennae Antennae function almost exclusively in sensory perception. Some of the information that can be detected by insect antennae includes: motion and orientation, odor, sound, humidity, and a variety of chemical cues. Antennae vary greatly among insects, but all follow a basic plan: segments 1 and 2 are termed the scape and pedicel, respectively. The remaining antennal segments ( flagellomeres ) are jointly called the flagellum.

48. Typical structure of Antennae

49. MODIFICATIONS OF INSECT ANTENNAE   1. Aristate   Aristate antennae are pouch-like with a lateral bristle. Examples: House and shore flies (order Diptera ). The antennae are important sensory structures used to detect air movement and odors. The antenna is three-segmented with a branched arista projecting dorsally from the third segment.

50. 2. Capitate or Knobbed or head shaped Capitate antennae are abruptly clubbed at the end. The antenna starts narrow at the base and gets bigger toward the tip, but only right near the tip. Examples: Butterflies (order Lepidoptera), sap beetles ( Coleoptera ).

51. 3. Clavate or Club shaped Clavate antennae are gradually clubbed at the end. Technically, the capitate antennae of butterflies are also clavate because they are also clubbed, but they’re a special kind of club and get their own name (they’re capitate clavate antennae) Examples: Carrion beetles (order  Coleoptera )

52. 4. Filiform or Thread like Filiform antennae have a thread-like shape. All the segments are of about the same thickness and have no prominent constrictions at the joints Examples: Ground and longhorned beetles (order Coleoptera ), cockroaches (order Blattodia ). Grasshoppers ( Orthoptera )

53. 5. Geniculate or Elbow like Geniculate antennae are hinged or bent like an elbow. Bents abruptly at an angel at the distal end of scape forming bent like knee or elbow Examples: Bees and ants (Hymenoptera), Weevils ( Coleoptera ) Ant's geniculate antennae

54. 6. Lamellate or plate like The last three segments extend in one side forming a leaf like structure Examples: Scarab beetles (order: Coleoptera )

55. 7. Moniliform Moniliform have a beadlike shape. Segments are more or less globular with prominent constriction between them Examples: Termites (order Isoptera ).

56. 8. Pectinate or comb shape The segments of pectinate antennae are longer on one side, giving each antennae a comb-like shape. The term pectinate derives from the Latin  pectin , meaning comb. Examples: Fire-colored beetles and fireflies (order : Coleoptera )

57. 9. Plumose or feather like Segments produce bunch of hairs from each joints Also called pinnate or bipectinate Examples: Moths (order Lepidoptera)and male mosquitoes (order Diptera ).

58. 10. Serrate Serrate antennae have a saw-toothed shape. Examples: Click beetles, mango stem borers (order Coleoptera ) .

59. 11. Setaceous or bristle like The size of segments decrease from the base to apex Examples: Dragonflies and damselflies (order Odonata ), cicada ( Hemiptera ), mayflies (order  Ephemeroptera )  

60. 1.Digestive system 2. Reproductive system, male 3. Reproductive system, Female 4. Respiratory system 5. Circulatory system 6. Nervous system and 7. Excretory system 8. Apiculture 9. Sericulture and 10. Lacculture Entomology and Pest Management Larry P Pedigo and Marlin E. Rice

61. MOUTH PARTS The mouthparts are the organs concerned for the ingestion of different nature of food. The variation can be correlated with the methods of feeding and the techniques of insect pest management. The mouthparts have also taxonomic importance as it gives clues for the classification of insects The mouth parts comprises the unpaired upper lip or labrum in front, the lower or ventral surface of which forms the epipharynx , a tongue like hypopharynx behind the mouth, a pair of jaws or mandibles, the paired maxillae and a labium forming a lower lip. The mouthparts may include up to two pairs of sensory, feeler-like palps (labial palps or maxillary palps ). Various pairs of glands (labial glands, mandibular glands, maxillary glands and thoracic glands) are also associated with the mouthparts. In insects, the mouthparts do not lie in a cavity of the head and the condition is called ectognathous . The mouth parts of Collembola , Diplura and Protura lie in a cavity of the head and the condition is called entognathous condition.

62. Figure : Insect mouth parts

63. Labrum: Labrum or upper lip is a broad lobe that covers the mandibles and closes the mouth cavity from the upper front. It helps to pull the food into mouth. b. Mandibles : Mandibles are the anterior or the first pair of true insect mouth parts and lie directly behind the labrum as the appendages of the second post-oral segment. Generally the mandibles are hard and heavily sclerotized , have various sets of teeth and brushes. Mandibles move sideways, can bite off and chew food particles. c. Maxillae : These lie directly behind the mandibles and are the appendages of the third post oral segment. The generalized type of maxillae is masticating structure which can be divided following well marked parts; Cardo : The triangular basal sclerite attached to the head capsule that serves as a hinge for the movement of the remainder of the maxillae. ii. Stipes : It is the central portion of the body of the maxillae. It is somewhat rectangular in shape. The stipes is situated above the cardo and is the basis for the remaining of the maxillae. Galea : It is the outer or lateral lobe articulating at the end of the stipes . It is frequently developed as a sensory pad or bears a cap of sense organs.

64. Lacinia : It is the inner or mesal lobe articulating at the apex of the stipes . It is usually mandible like in form with a series of spines or teeth along its mesal edge. Palpus : It is the antennae like segmented appendage which arises from the lateral side of the stipes . It is commonly five segmented and entirely sensory in function. d. Labium: Labium or lower lip is a single structure lying posterior the maxillae and is formed by the fusion of a pair of appendages serially homologous with the maxillae. The labium is divided by a labial suture into two primary portions: a basal postmentum and distal prementum . Postmentum : It is the basal region of labium and hinges with the head membranes. ii. Prementum : It is the apical region of the labium and includes various lobes and processes. The central portion is the prementum also called stipulae which bears a pair of labial palpi , one on each side of the prementum and each usually three segmented in generalized forms. The apical portion of prementum frequently forms a sort of tongue and is called ligula . The ligula varies greatly in structure but usually is divided into two pairs of lobes: the mesal glossa and lateral paraglossae parallel to glossae . In many groups the glossae are fused to form an alaglossa and in many others the glossa and paraglossa are fused to form totoglossa .

65. Epypharynx : On inner and posterior side of labrum a membranous median lobe, epipharynx is present. Epipharynx is a sensory area believed to contain end organs of taste. Hypopharynx : Hypopharynx is a short tongue like structure located immediately above the labium and between the maxillae. It usually forms a project lobe or mould and is associated with the base of labium as to be considered a part of it. Unlike the other mouth parts, the hypopharynx is not an appendage but an un-segmented outgrowth of the ventral membranous floor of the head. In most insects, the ducts from salivary glands open on or near the hypopharynx . In a few primitive insects, a pair of lateral lobes occurs with the median lingua of hypopharynx and is called superlinguae .

66. Modification of mouth parts The most important way in which insects inflict losses and injury upon man and his possessions is by eating or feeding. The mouth part of an insect can be classified in accordance with their function. Mouthparts very greatly among insects of different orders but there are two main functional groups: mandibulate and haustellate . Haustellate mouthparts can be further classified as follows: Stylet : Piercing-sucking: e.g. Mosquito Rasping-sucking: e.g. Thrips b) Non- stylet Siphoning: e.g. Butterflies Sponging: e.g. House fly Chewing-lapping: e.g. Honey Bee

67. Stylets are needle-like projections used to penetrate plant and animal tissue. The modified mandibles, maxilla, and hypopharynx form the stylets and the feeding tube. After piercing solid tissue, insects use the modified mouthparts to suck liquids from the host.

68. MANDIBULATE MOUTH PART Mandibulate (Biting and chewing) mouthparts are used for biting and grinding solid foods. Examples: Dragonflies and damselflies (order Odonata ), Termites (order Isoptera ), Adult lacewings (order Neuroptera ), beetles (order Coleoptera ), Ants (order Hymenoptera), Cockroaches (order Blattaria ), Grasshoppers, crickets and katydids (order Orthoptera ) Caterpillars (order Lepidoptera). Adult Lepidoptera have siphoning mouthparts.

69. Piercing-sucking mouthparts Piercing-sucking mouthparts are used to penetrate solid tissue and then suck up liquid food. Examples: Cicadas, aphids,  and other bugs (order Hemiptera ), sucking lice (order Phthiraptera ), stable flies and mosquitoes (order Diptera ). These group of insects are also called drinkers

70. Labrum: It is a short flap or triangular lobe that covers the labium groove towards the base Mandibles and Maxillae: The mandibles and maxillae are long, slender and form delicate, hollow needle or bristle like stylets four in number The piercing-sucking needle is formed from four hairlike stylets fitted closely together The outer stylets are derived from mandibles and the inner stylets are derived from maxillae Mandibles are chief piercing organs The maxillae are double grooved on the inner face and when held together, form two channels; one is for the passage of saliva into plant to facilitate food flow and digestion and the other is for the uptake of plant juices. c) Hypopharynx : At the posterior part of the beak, between the bases of the piercing stylets , there is a small conical lobe Anterior wall of hypopharyns is continued dorsally into the chamber of sucking pumps d) Labium: The labium forms a protective sheath for the stylets . Plant feeders like leafhoppers, aphids and scales have the same basic mouth part structure and many inject viruses and other disease-causing organisms into the plant along with their saliva

71. Rasping and sucking mouth parts Rasping and sucking mouthparts are a form of the piercing-sucking type and are found in thrips ( Thysanoptera ) Thrips have asymmetrical  mouthparts  that are also unique to the group. The right  mandible  of thrips is reduced– and in some species completely absent. Thrips mouth parts have a cone shaped beak formed from the clypeus ( a plate above the labrum in chewing insects), labrum, parts of the maxillae and the labium This beak contains the maxillae, hypopharynx and the left mandible; together this structure forms a stylet Thrips use the beak to rasp host tissues and take up liquid food through stylet .

72. Chewing and Lapping Found in bees and wasps and is modified for taking solid and liquid food like pollen, nectar and honey Labrum: Similar to chewing type mouth part Mandibles: Similar to chewing type mouth part but become more or less flattened to form tools useful in molding wax, manipulating nest materials and grasping prey 3) Maxillae and labium: Galea , labial palps and glossa are elongated and modified to make five part long cylindrical tongue for lapping up nectar Galeae form a pair of blade like structure The paraglossae are greatly reduced and glossae greatly elongated to form a united hairy, flexible, tongue which terminated distally to a honey spoon or flabellum and can be rapidly protracted and retracted to reach deep into the nectarines of tubular flowers

73. Feeding mechanism: A temporary food channel in formed by the concave inner surface of the galea roofing over glossa and fitting lenghwise against the labial pulps. By such the complexly formed tube suck up the nectar or honey In general bees thrust out the glossa or tongue on open nectarines and licks out the nectar with the tip Many other state that the liquid food ascends capillary action thorough the ventral canal of the glossa and glossa is shortened by a muscular pull on the inner rod squeezing the nectar upward to enter the space between the glossa and the base of paraglossa

74. Chewing and Lapping

75. Siphoning The mouth parts of adult butterflies and moths are elongated and stylet like to form highly specialized proboscis for sucking up liquid without piercing Labrum and mandibles: Labrum greatly reduced and mandible in imperfect Maxillae: Galea greatly elongated to form slender hollow tube, the proboscis which is only the essential sucking part but not capable for piercing. The maxillary pulps are rudimentary Labium: The labium is represented only by the large hairy or scaly three segmented labial palps with very small basal plate

76. Proboscis One of the more defining characteristics of Lepidopterans is their coiled proboscis. It is held coiled under the head when not in use. During feeding, however, it is extended to reach the nectar of flowers. The proboscis is a long tube that is formed by heavily modified maxillae, specifically the galea .

77. Sponging The mouth parts are fitted for using only foods which are either liquid or readily soluble in saliva. Eg . House fly, non blood sucking Muscidae , Syrphidae and many dipterans The mandibles and maxillae are non functional and the remaining parts form proboscis with fan-shaped sponge at the tip Liquid fluid is “mop up” by the capillary action of this sponge If not liquid, salivary secretions through the mouthparts make it so. Labium: On lower side of the head, there is a fleshy, elbowed and retractile proboscis which is the major mouth part and is the labium. The end of the labium is specialized into a large sponge like apex the labella The labella are transverse by a series of furrows and channels forming capillaries which convey the liquid food to the food channel Labrum, epipharynx and hypopharynx : The interlocking of the elongate epipharynx and hypopharynx together form two stylets which function as food sucking channel but are incapable of piercing the host tissues Feeding Mechanism : Capillary action

78. Cutting and sponging In horse flies and certain other Diptera , are similar to sponging type but have well developed mandibles forming sharp blades and maxillae forming probing stylets Together these structures cut and tear the skin of mammals, causing blood to flow The blood is collected by the sponge like development of labium and conveyed to the hypopharynx The hypopharynx and epipharynx fit together to form a tube through which the blood is sucked into the oesophagus

79. Visual Organs or Photoreceptors The eyes general are sensitive to light rays and transmit the effect on its sense cells to the central nervous system The eyes are thus also called photoreceptors or light perceiving organs. Photoreceptors of insects includes 1. Compound eyes 2. Simple eyes or dorsal ocelli 3. Lateral ocelli or stemmata

80. Ocelli -- Simple eyes Two types of "simple eyes" can be found in the class Insecta :    dorsal ocelli  and  lateral ocelli (=stemmata) .   Although both types of ocelli are similar in structure, they are believed to have separate phylogenetic and embryological origins. Dorsal ocelli  are commonly found in adults and in the immature stages (nymphs) of many hemimetabolous species.   They are not independent visual organs and never occur in species that lack compound eyes.   Whenever present, dorsal ocelli appear as two or three small, convex swellings on the dorsal or facial regions of the head.   They differ from compound eyes in having only a single  corneal lens  covering an array of several dozen rhabdom -like sensory rods .   These simple eyes do not form an image or perceive objects in the environment, but they are sensitive to a wide range of wavelengths, react to the polarization of light, and respond quickly to changes in light intensity.   No exact function has been clearly established, but many physiologists believe they act as an "iris mechanism" -- adjusting the sensitivity of the compound eyes to different levels of light intensity.

81. Ocelli -- Simple eyes Lateral ocelli (=stemmata)  are the sole visual organs of holometabolous larvae and certain adults ( e.g.   Collembola , Thysanura , Siphonaptera , and Strepsiptera ).   Stemmata always occur laterally on the head, and vary in number from one to six on each side.   Structurally, they are similar to dorsal ocelli but often have a  crystalline cone  under the  cornea  and fewer sensory rods .   Larvae use these simple eyes to sense light intensity, detect outlines of nearby objects, and even track the movements of predators or prey.   Covering several ocelli on each side of the head seems to impair form vision, so the brain must be able to construct a coarse mosaic of nearby objects from the visual fields of adjacent ocelli . 

82. Dorsal ocelli Lateral ocelli (=stemmata)

83. Compound Eyes A pair of  compound eyes  are the principle visual organs of most insects; they are found in nearly all adults and in many immatures of ametabolous and hemimetabolous orders.   As the name suggests, compound eyes are composed of many similar, closely-packed facets (called  ommatidia ) which are the structural and functional units of vision.   The number of ommatidia varies considerably from species to species:   some worker ants have fewer than six while some dragonflies may have more than 28,000. Externally,each ommatidium is marked by a convex thickening of transparent cuticle, the  corneal lens .   Beneath the lens, there is often a  crystalline cone  secreted by a pair of  semper cells .   Together, the lens and the crystalline cone form a  dioptric apparatus  that refracts incoming light down into a receptor region containing visual pigment. Primary pigment cells (or) Iris pigment cells: These are darkly pigmented cells, commonly two in number, present around the crystalline cone which are mainly useful for separating the ommatidia from one another and also restrict the movement of light passing from the neighboring ommatidia . The light-sensitive part of an ommatidium is called the  rhabdom .   It is a rod-like structure, secreted by an array of 6-8 specialized neurons (  retinula cells )

84. Compound Eyes  The rhabdom contains an array of closely packed microtubules where light-sensitive pigments (e.g. rhodopsin , etc.) are stored. The retinular cells continue with the axons that pass through the basement membrane forming an optic nerve which remain connected to the optic lobes of the brain. Most diurnal insects have  pigment cells  surrounding each ommatidium .   Secondary pigment cells: The rhabdom is surrounded by secondary pigment cells that help to separate the ommatidia . They surround the retinular and primary pigment cells. These are numerous in number. Nocturnal and crepuscular (are those that are active primarily during  twilight  -i.e.,  dawn  and  dusk ) insects have pigment cells that do not completely isolate each facet.   Their ommatidia are stimulated by light from larger fields of view.   This produces a brighter but theoretically less distinct mosaic image. They can detect polarization patterns in sunlight, and discriminate wavelengths in a range from ultraviolet to yellow (but not red). 

85. Difference between Simple Eyes and Compound Eyes Compound eyes are made up of clusters of ommatidia , but simple eyes are made up of only one single unit of eye. Compound eyes are found in most of the arthropods, annelids and molluscs . However, simple eyes are found among many types of organisms including most of the higher vertebrates. Compound eyes can cover a wider angle compared to simple eyes. The types of simple eyes are more diversified than the compound eyes. The polarization of sunlight could be understood via compound eyes, but not through simple eyes.

86. THORAX AND THORACIC SEGMENTS AND ITS APPENDAGES The thorax is the middle body region between the head and abdomen. The insect  thorax  has three segments: the  prothorax ,  mesothorax , and  metathorax . The  anterior  segment, closest to the head, is the prothorax ; its major features are the first pair of legs and the  pronotum . The middle segment is the mesothorax ; its major features are the second pair of legs and the anterior wings, if any.  The third, the  posterior , thoracic segment, abutting the abdomen, is the metathorax , which bears the third pair of legs and the posterior wings. Each segment is delineated by an intersegmental suture.

87. THORAX AND THORACIC SEGMENTS AND ITS APPENDAGES Each segment has four basic regions A thickened dorsal plate on each segment of the body of an insect is called the tergum (or notum ) to distinguish it from the abdominal terga . [ The two lateral regions are called the pleura (singular: pleuron ) and The ventral aspect is called the sternum. In turn, the notum of the prothorax is called the pronotum , the notum for the mesothorax is called the mesonotum and the notum for the metathorax is called the metanotum . The legs arise on pleura and wings articulated between notal and pleural region Continuing with this logic, there is also the mesopleura and metapleura , as well as the mesosternum and metasternum .

88. Structure of legs The  fore-legs  are located on the prothorax , the mid-legs  on the mesothorax and t he hind legs  on the metathorax . Each leg has six major components, listed here from proximal to distal:  Coxa : It is the basal segment articulated with the thorax in the pleural region. The parts of coxa is divided into two parts- the posterior and anterior ( neron ). Trochanter : It is the small second segment articulated with coxa and forms an immobile attachment with the femur distally. Femur : It is the first thickest, largest and stoutest segment of insect leg. Tibia : It is the slender and second longest shank of the leg articulated with the femur by dicondylic joint. Tarsus : Tarsus or foot is the subdivided into from two to five tarsomeres . The basal tarsomere , the basitarsus is articulated with tibia by a single condyle but other tarsomeres are connected by flexible membrane and can move freely. The distal end of tibia contains prominent spines or spurs that help to maintain a footing. Pretarsus : It is the end of the tarsus that bears claws and pegs and is placed flat upon the ground when walking. Pretarsus usually bears two sharp curved hooks or claws between them some complicated pads also known as pulvulli , arolia or empodia which are very important in locomotion. In some insects like house fly, the arolia bear tiny hollow hairs that exude sticky substance.

89. Modification of legs 1. Fossorial or digging : nsects with fossorial legs live underground and use their highly modified legs, usually the forelegs, to dig burrows. The legs modified for digging are best known in mole crickets ( Gryllotalpa africana ) and dung beetles. In Gryllotalpa , the forelegs are very short and broad, the tibia and tarsomeres bearing stout lobes which are used in digging The basic walking legs show modifications in various ways to serve different functions. The followings are the major: 2. Cursorial or walking-running type : Cursorial legs tend to be long and narrow and are designed so that the insect can move very quickly. It has five segmented tarsus, both femur and tibia bears spines. Example: mesothoracic legs of cockroach, Periplanteta amenricana , ground and tiger beetles (order  Coleoptera ).

90. Modification of legs Saltatorial or jumping type: Hind Femur is greatly enlarged. Saltatorial legs work well for jumping because they are enlarged legs filled with bulky, strong muscles.  All those muscles allow insects with this type of leg to jump, propelling themselves forward very long distances very quickly. The power for jumping is provided by sudden extension of the hind tibia. Example: hind legs of grasshopper, Hieroglyphus banian .   4. Raptorial or grasping legs : Coxa is elongated, femur and tibia bear rows of spines.This type of leg modification is found in predatory insects and helps in catching the prey. Example: the forelegs of praying mantids , Mantis religiosa and water scorpion.

91. Modification of legs 5. Natatorial or swimming: Natatorial is another word for swimming, so insects with natatorial legs are aquatic insects that require modified legs to move easily through water. Coxa is long, tibias and tarsi bear hears and flattened to form an oar like structure for swimming. Example: the hind legs of water scavenger beetle. Scansorial or clinging type : Tarsus is single segmented and terminated into a powerful claw for clinging. Example: fore legs of body louse, Haematopinus suis .

92. Modification of legs 7. Polleniferous or pollen carrying : The femur and tibia of hind legs are provided with brush like hairs, the tibia is broadened with concave outer surface fringed with long curved spines and acts as pollen basket. A comb in the inner side of pretarsus is used for pollen collection. A rake at the base of tibia is used for scrapping and collecting pollen in the pollen basket. Example: the workers of Apis mellifera .

93. Notum : The tergum or dorsum of particularly thoracic segments Alinotum : The wing bearing plate of the dorsum of the mesothorax or metathorax of pterygotes insects Postnotum : The post scutellar , phragma bearing plate often present in the dorsum of an alate segment, derived from the anterior part of the following tergum . Also called phragmanotum or post scutellum Epimeron : The area of pleurone posterior to the pleural suture sometimes divided horizontally into a supra-, an- and infra or kat-epimeron Episternum : The area of pleuron before the pleural suture and above the trochantin sometimes divided horizontally into supra-, an- and infra or kat-episternum Prescutum : The anterior area of mesonotum or metanotum between the antecostal suture and prescutal suture, when the latter is present Scutum : The area of alinotum anterior to the suture of the V-shaped notal ridge or between this suture and prescutal suture if the latter is present Scutellum : The area of alinotum posterior to the suture of the Y-shaped notal ridge or the corresponding area when the ridge is incomplete or absent.

94. 1. Ambulatorial (Walking leg):  e.g. Fore and middle legs of cockroach. Femur and tibia are long. Legs are well developed similar in form. 2. Cursorial (Running leg):  e.g. All three pairs of legs of Ants. Femur in not swollen. All the legs are long. 3. Saltatorial (Jumping leg):  e.g. Hind leg of grasshopper, field cricket, Trochanter is fused with femur. Hind femur is enlarges. 4. Scansorial ( Clining leg):  e.g. All three pairs of legs of head house. Tibia is stout and at one side bears a thump like process. The tarsus is single segmented. There is a single large claw that usually fits against a thumb-like process, which forms an efficient mechanism for hanging on to the hairs of host. 5. Fossorial (Digging leg):  e.g. Fore legs of mole cricket. Femur is shout. Tibia is short and shout and bears distally two or three strongly printed tines. The first two segments of tarsus are also produced into strong tines. The first two segments of tarsus are also produced into strong tines. Tympanum is present on fore mantids . 6. Raptorial (Grasping leg):  e.g. Fore legs of preying mantids . Fore legs are of no use in locomotion. Coxae elongated to give an extended reach to capture the prey. The femur is large and groove when it snaps down over the prey. Tarsus consists of five tarsomeres . 7. Natatorial (Swimming leg):  e.g. Hind legs of water bug or water. Beetle, Femur, tibia and first four tarsomeres are all broad and flattened. Their edges are provided with flattened setae. The hind legs serve as oars. 8. Sticking leg:  e.g. All the three pairs of legs of housefly. Pretarsus consists of a pair of lateral adhesive pads called pulvilli and a pair of claw. Arolium is absent. But a median spine like structure called campodium is present. The pulvilli are covered with dense mats of tiny glandular hairs called tenant hairs. Secretions of these glandular hairs are helpful in clinging to smooth surfaces and to walk upside down on the ceiling. 9. Basket-like leg :  e.g. Legs of dragonfly and damselfly Legs are situated just being the head and are anterior in position. Legs are spiny and closely placed which are useful in seizing the prey during flight. Legs are not useful in locomotion. 10. Foragial leg:  (Pollens collecting and carrying leg) e.g. legs honey bee. a. Eye brush: Hairs on tibia useful to clean the compound eyes. b. Antenna cleaner: Velum is a movable clasp present at distal end Tibia. Antenna c. c. comb semicircular notch lined with small spines. d. Pollen brush: Bristles on basitarsus from the pollen brush which is useful to collect pollen from the head and mouth parts.

95. WINGS Insects are the only invertebrates that can fly.  Most insects have two pairs of wings -- one pair on the mesothorax and one pair on the metathorax (never on the prothorax ) except flies and a few other groups, which have only one pair. Some insects are wingless eg . Apteygota Except for may flies , all immature insects lack functional wings The wings may be membranous, parchment-like, heavily sclerotized , fringed with long hairs, or covered with scales.  Wings serve not only as organs of flight, but also may be adapted variously as protective covers ( Coleoptera and Dermaptera ), thermal collectors (Lepidoptera), gyroscopic stabilizers ( Diptera ), sound producers ( Orthoptera ), or visual cues for species recognition and sexual contact (Lepidoptera). In most cases, a characteristic network of veins runs throughout the wing tissue. These veins are extensions of the body's circulatory system.  They are filled with hemolymph and contain a tracheal tube and a nerve.  In membranous wings, the veins provide strength and reinforcement during flight. Wing shape, texture, and venation are quite distinctive among the insect taxa and therefore highly useful as aides for identification. Termites and certain ants break off their wings after a single nuptial flight. In many others, only one sex has wings and the other sex is wingless. Some insects have only one pair of wings but no insect has more than four wings

96. Longitudinal veins: The longitudinal veins vary somewhat in their method of branching in different insects but the basic arrangement is as follows: 1. Costa (C)  – the leading edge of the wing 2. Subcosta (Sc)  – second longitudinal vein (behind the costa ), typically unbranched 3. Radius (R)  – third longitudinal vein, one to five branches reach the wing margin 4. Media (M)  – fourth longitudinal vein, one to four branches reach the wing margin 5. Cubitus (Cu)  – fifth longitudinal vein, one to three branches reach the wing margin 6. Anal veins (A1, A2, A3)  – unbranched veins behind the cubitus Wing venation

97. Cross veins: The cross veins are named according to their location in the wing or the longitudinal veins they connect. 1. Humeral (h): It is the cross vein run between the costa and subcosta 2. Radial (r): It connects R1 and the anterior branch of the radial sector. 3. Sectoral (s): It connects the longitudinal radius veins R3 and R4 4. Radio-medial (r-m): It connects the posterior branch of the radius and the anterior branch of media 5. Media (m): It connects longitudinal veins media M2 and M3. 6. Media- cubital (m-cu): It connects the posterior branch of media and the anterior branch of the cubitus 7. Cubito - anal (cu-a): It connects the posterior branch of the cubitus and the first anal vein Wing venation

98. Characteristic Appearance Order(s) Elytra  -- hard, sclerotized front wings that serve as protective covers for membranous hind wings Coleoptera   and  Dermaptera Hemelytra  -- front wings that are leathery or parchment-like at the base and membranous near the tip Hemiptera : Heteroptera ( true bugs) Tegmina  -- front wings that are completely leathery or parchment-like in texture Orthoptera, Blattodea, and Mantodea Halteres  -- small, club-like hind wings that serve as gyroscopic stabilizers during flight Diptera Fringed wings  -- slender front and hind wings with long fringes of hair Thysanoptera Wing adaptations and modifications:

99. Membranous : Both fore- and hind wings are thin, firm and more or less transparent. Example: Odonata (dragonflies) Scaly wings  -- front and hind wings covered with flattened setae (scales) Lepidoptera Hamuli  -- tiny hooks on hind wing that hold front and hind wings together Hymenoptera Stigma : Thickened opaque spot along the costal margin of equal sized, net veined, membranous wings. Example: dragonflies and damselflies

100. ABDOMEN The insects abdomen is the third region of the insect body and is often longer than head and thorax Insects abdomen usually consists of six (Collembolas) to ten segments and terminaes in the paraproct, whre the anus opens This paraproct may form a lobe like epiproct above the anus and a pair of leteral paraprocts around it. The dorsal and ventral abdominal segments are termed terga (singular tergum) and sterna (singular sternum), respectively.  Spiracles usually can be found in the conjunctive tissue between the terga and sterna of abdominal segments 1-8. Reproductive structures are located on the 9th segment in males (including the aedeagus , or penis, and often a pair of claspers) and on the 8th and 9 th  abdominal segments in females (female external genitalia copulatory openings and  ovipositor ).  Ovipositor   The ovipositor is the egg-laying device found only in female insects. In some insects, the ovipositor is highly modified and conspicuous. In others, the apparatus may be needle or blade-like.

101. Insects Abdomen

102. Abdominal Appendages Abdominal appendages of insects can be grouped as Pre-genital appendages Genital appendages Post genital appendages

103. Contd …. Pre-genital appendages: Appendages prior to eight segments Styliform appendages : In primitive apterygotes or in non-insect hexapods, there are pairs of small, unjointed styli each inserted on a basal sclerite called coxa along with eversible vesicles Collembolan appendages: On the third abdominal segments , a median love called ventral tube projects and at its tip long and tubular eversible vesicles are present in pair Cornicles or siphunculi : P aired secretory structures located dorsally on the abdomen of aphids It project from the dorsum of 5 or 6 or from between them and have defensive function in most cases. The cornicles produce substances that repel predators or elicit care-giving behavior by symbiotic ants.

104. Contd …. d) Gills : R espiratory organs found in the nymphs (naiads) of certain aquatic insects. In Ephemeroptera (mayflies), paired gills are located along the sides of each abdominal segment In Odonata (damselflies), the gills are attached to the end of the abdomen. Many larvae of aquatic insects like mayflies may have 6 or 7 pairs of plate like or filamentous gills. The gills have direct role in gaseous exchange and more importantly to maintain a flow of water over the body. e) Prolegs or pseudolegs : Except to the three pairs of thoracic legs, leg like outgrowths of the body wall in abdominal region are the feature of many holometabolous insects and are called prolegs or pseudolegs or non-thoracic legs or temporary legs. They are fleshy, locomotory appendages found only in the larvae of certain orders (notably Lepidoptera, but also Mecoptera and some Hymenoptera). Based on number of prolegs the larvae are categorized to 1) caterpillar : Larvae with 5 pairs of prolegs one pair each on 3-6 and 10 segments, example: cabbage butterfly larvae 2) Pseudo caterpillar: The larvae with 6-9 pairs of legs one pair each on 2 to 7th and 10th segments, example: sawfly 3) Loopers : Only two pairs one pair each on 6th and 10th segments, example: inch worm larvae. 4) Semiloopers : The larvae have three pairs of prolegs , example: cabbage semi- loopers

105. Genital appendages The reproductive openings and genitalia are found on the ninth abdominal segment in male and on eight and ninth abdominal segments in the female are commonly called genital appendages The insect's genital opening lies just below the anus:   it is surrounded by specialized sclerites that form the external genitalia.   In females, paired appendages of the eighth and ninth abdominal segment fit together to form an egg-laying mechanism called the ovipositor   These appendages consist of four valvifers (basal sclerites with muscle attachments) and six  valvulae (apical sclerites which guide the egg as it emerges from the female's body). In males, the genital opening is usually enclosed in a tube-like  aedeagus  which enters the female's body during copulation (like a penis).   The external genitalia may also include other sclerites (e.g. subgenital plate, claspers, styli, etc.) that facilitate mating or egg-laying.   The structure of these genital sclerites differs from species to species to the extent that it usually prevents inter-species hybridization and also serves as a valuable identification tool for insect taxonomists.

106. Contd …. Post genital appendages Cerci  (singular  cercus ) are paired  appendages  on the rear-most segments of many  Arthropoda , including  insects  and  Symphyla . Many forms of cerci serve as sensory organs, but some serve as pinching weapons or as organs of  copulation . [1] In many insects they simply may be functionless  vestigial structures . Most cerci are segmented and jointed, or filiform (threadlike), but some take very different forms. Some  Diplura , in particular  Japyx  species, have large, stout forcipate (pincer-like) cerci that they use in capturing their prey. [3] The cerci of two sexes may differ in many insect species or have dimorphism

107. Contd …. Crickets  have particularly long cerci while other insects have cerci that are too small to be noticeable. However, it is not always obvious that small cerci are without function; they are rich in sensory cells and may be of importance in guiding copulation and  oviposition .

108. Contd …. Median caudal filament This is a thread like projection arising from the center of the last abdominal segment between the cerci. Some insects such as  mayflies , silverfish and  bristletails  have an accompanying third central tail filament which extends from the tip of the  abdomen . Urogomphi  (Singular  urogomphus ;) Greek  oura , tail; gomphos , club): ( Arthropoda :  Insecta ) In Coleoptera larvae, a pair of outgrowths of the  tergum   of segment  9 in the form of short spines or  multiarticulate  processes Also referred as pseudocerci ; corniculi .

109. Contd …. Terminal spines: The 10 th abdominal segment of hawk moths and jet moths bear spine like structures Used for defense

110. Insect Metamorphosis and Development The majority of insects start life in the form of a fertilized egg laid by a female. After hatching of the egg the developing young one undergoes a series of changes in size and structure before becoming adult. Each time an insect makes a change into the next growth stage, it has to molt (shed) its skin. After each molt, the insect becomes a little larger and somewhat different in form until it reaches the adult stage. After it reaches the adult stage, it does not molt or grow any more. To the series of changes which takes place in the life history of an insect the term metamorphosis has been applied. There are four kinds of metamorphosis, complete (butterflies), gradual (grasshoppers), incomplete (dragonflies) and no metamorphosis (Silverfish). The exact style of metamorphosis is not the same for all insects, but insects in the same order have the same style of metamorphosis.

111. Contd …… Ametabolous Some orders of insects are said to have no metamorphosis ( Ametabolous development ) because there is little or no difference in appearance between the young stages and the adult except for size. The no-metamorphosis model is found in primitively wingless insects (Subclass Apterygota ). Suitable examples are primitive insects such as silverfish ( Thysanura ) sprint tails etc.

112. Contd …. Gradual metamorphosis ( Paurometabolous ) The life cycle of insects with gradual metamorphosis have three life stages: egg, nymph and adult. (Aphid, grasshoppers, termites) Nymphs resemble the adult except that their body parts are out of proportion with each other, and they do not have fully developed wings and external genitalia. With each molt, the nymphs gradually develop wings and take on the body proportions of an adult. Nymphs have the same type of mouthparts as the adult, and they both feed on the same kind of food. Fig. The life cycle of a plant bug

113. Contd ….. Incomplete metamorphosis ( Hemimetabolous development ) is somewhat like gradual metamorphosis and also has three life stages: egg, naiads and adult . However, the adult insect with incomplete metamorphosis lays its eggs in or near water and the naiads develop in water. The adults are flying insects that live out of water. Naiads and adults therefore do not eat the same kind of food. Naiads have chewing mouthparts, but the adults have differently shaped chewing mouthparts or no functional mouthparts. The naiad and the adult usually differ a lot in appearance although the naiads gradually develop wings. Eg . Dragonflies, Mayflies, Stoneflies

114. Complete metamorphosis ( Holometabolous ): It has four distinct form stages: egg, larvae, pupa and adult . The larval stages do not look like the adult at all, and they are often worm-like. Larvae often have different mouthparts and food habits than the adult, and they often live in places different from the adult. Larvae molt several times and get a little larger with each molt, but there is no gradual development of wings or other adult characteristics. When a fully grown larva molts, it changes into a pupa. The pupa usually does not eat or move around much, but a lot of internal changes take place. When the pupa has made all its internal changes, its skin splits and the fully formed adult emerges. Most insects with complete metamorphosis are winged in the adult stage. The adults do not molt or grow any more. Little flies or beetles, for instance, do not grow to become larger. Flies ( Diptera ), beetles ( Coleoptera ), wasps (Hymenoptera) and butterflies (Lepidoptera), have holometabolic life cycles.  

115. Fig. Complete metamorphosis

116. Heterometabolous : (of an insect) undergoing incomplete metamorphosis in which the nymph is essentially like the adult and there is no pupal stage Hypermetamorphosis : This is specialized type of metamorphosis found in higher orders of Endopterygota insects. It is a type of complete metamorphosis in which different larval instars represent two or more markedly different types of larvae. The first instars larva is active and usually campodaeiform and the subsequent larval instars are vermiform or scarabaeiform e.g. blister beetles.

117. Types of Larvae Holometabolous insects have four stages of development from egg to adult. The immature stage between egg and pupa is known as larva , and the other one between larva and adult is called pupa . The larvae are generally voracious feeders where as pupae do not feed at all. There are various types of larvae and of pupae.

118. Types of Larvae Types of larvae: There are three main types of insects larvae namely oligopod , polypod and apodous . A Oligopod : Thoracic legs are well developed. Abdominal legs are absent. There are subtypes: Campodiform : Larvae are elongated, somewhat flattened and legs are well developed. Example: Lady bird beetle larvae Scarabaeidiform : Having short thoracic legs and C-shaped body, these larvae are known as grubs. Example: White grubs. Elateriform : Having elongated, cylindrical long body with tough shin, popularly known as wireworms. Example: click beetle larvae

119. Contd …. B. Polypod - They possess thoracic and abdominal legs ( prolegs ): Pseudocaterpillar : Larvae having 3 pairs of thoracic legs and 6 to 9 pairs of prolegs . Example: Sawfly larvae Caterpillar: Besides 3 pairs of thoracic legs, they possess 5 pair of prolegs . Example: Cabbage butterfly larvae Semilooper : Having 3 pairs of thoracic legs, and 3 pairs of prolegs . Example: Cabbage semi- loopers Looper : They have 3 pairs of thoracic legs and only 2 pairs of prolegs . Example: Inch-worm larvae 

120. Contd …. Apodous : Larvae lacking both thoracic legs and prolegs . Eucephalous : Well sclerotized head capsule. Example: Cerambycidae ( round headed bettle ) Hemicephalous : Head slightly reduced. Example: Honey bee larvae Acephalous : Head greatly reduced. These larvae are called maggots. Example: Housefly maggots

121. Quiescence and Diapause Diapause : Diapause is a mechanism used as a means to survive predictable, unfavorable environmental conditions, such as temperature extremes, drought or reduced food availability Diapause is not only induced in an organism by specific stimuli or conditions Once it is initiated, only certain other stimuli are capable of bringing the organism out of diapause . Generally the pattern of diapause is determined by genetic costitution and the diapause period may last several months to a year or more

122. Types of Pupae A. Based on adherence of appendages Exarate : Body appendages loosely attached or or extended freely from any secondary attchments to the body. Example: Bees, Wasps, Beetles, etc Obtect : Body appendages firmly attached to the body. Example: Lemon butterfly pupa, moth pupa Coarctate : Pupa covered in a hardened exuviae (skin) of the last larval instars. Example: Housefly Pupa

123. PUPAL PROTECTION In general pupal stage lacks mobility. Hence, it is the most vulnerable stage. To get protection against adverse conditions and natural enemies, the pupa is enclosed in a protective cover called cocoon. Based on the nature and materials used for preparation of cocoons, there are several types: S.No Types of cocoon Materials used Example 1 Silken cocoon silk silkworm 2 Earthen cocoon Soil and saliva Gram pod borer 3 Hairy cocoon Body hairs Wolly bear 4 Frassy cocoon Frass + saliva Coconut black headed caterpillar 5 Fibrous cocoon Fibres Red palm weevil 6 Puparium Hardened last larval skin House fly

124. Quiescence Quiescence: A temporary arrest of growth and development at any stage in the live cycle by adverse conditions like drought, starvation, lack of nutrients or essential substances, temperature Quiescence is abruptly terminated by stimuli In oriental fruit moth quiescence of larvae is controlled by temp. and photoperiod and darkness break it.

125. INSECT CLASSIFICATION AND ECONOMICALLY IMPORTANT ORDERS WITH FAMILIES

126. All living organisms are placed into certain groups or categories for classification and identification. The seven most commonly used categories are:   Kingdom - Animal Phylum – Arthropoda Class – Insecta Order – Lepidoptera (Butterflies and moths) Family – Noctuidae Genus – Helicoverpa Species – armigera The species is the basic taxonomic category and may be defined as groups of actually interbreeding natural populations which are reproductively isolated from other such groups. Closely related species are grouped together in the next higher category – the genus. Related genera make up a family and related families are grouped into orders. The scientific name of an organism consists of two words – the generic name and the specific name. This system of naming insects is called the binomial system of nomenclature.

127. Insect orders The classification of insects into various orders is based on the presence or absence of wings, wing venation, the type of metamorphosis, the type of mouth parts, the characters of antennae, tarsi, etc. Thus we have:   Class: INSECTA Sub-class: APTERYGOTA (Wingless) Sub-class: PTERYGOTA (Winged)

128. Metamorphosis The  apterygota  have no metamorphosis. Except for the size, all larval stages closely resemble the adults (which are wingless). The  exopterygota  undergo a simple metamorphosis. In molting from egg, via the nymphal stages to an adult, there is a gradual change in the external appearance. The late nymphal stages already show the development of wing pads. But only in the last molt functional wings are developed. The nymphs usually have the same feeding habits as the adults. In the  endopterygota  there is a complete metamorphosis. In these insects the external (and internal) changes during the life history are the greatest. The eggs hatch into larvae which feed actively during the different instars. The larvae may or may not have legs. The development of wings is not visible during the larval stages. After several molts a pupa is formed. A pupa is an inactive stage, it does not feed and it does not move. Sometimes the pupa is protected by a cocoon of silk, or it is found in an earthen cell in the soil. During this pupal stage big changes take place internally. After the pupal stage, a highly active winged adult appears. Often, the larvae and the adults live in different types of habitat and use different types of food.

129. Sub-class: APTERYGOTA (Wingless) Insect Order Example(s) Characteristics Protura Telson tails, Proturans Tiny , flightless insects that feed on decayed organic matter. They have cone-shaped heads that lack antennae. Diplura Japygids , Diplurans Minute insects that are mainly active at night. Found worldwide, usually in soil, they typically have white bodies, long antennae, and no eyes or wings Collembola Snow-fleas, Springtails Oldest known group of insects. They have drab colors, are able to leap, and usually live in soil, where they feed on decomposing plant matter. Thysanura Silverfish Characterized by long antennae and tapering bodies covered in tiny scales.

130. None of them are of economic importance, except silverfish Which occasionally damage book-bindings. The subclass PTERYGOTA is further divided into two groups as: EXOPTERYGOTA (Simple body change during growth) ENDOPTERYGOTA (Complex body change during growth)

131. EXOPTERYGOTA (Simple body change during growth) EXOPTERYGOTA includes 16 insect orders Order: Eph e me r opte r a ( Ephemero : living for a day, ptera : wing) Example : Mayflies Characteristics : Fragile insects with two pairs of wings: a triangular front pair and a rounded rear pair. The nymphs are aquatic, with tracheal gills. In many species, adults die within hours or days after reaching maturity.

132. Contd … 2. Order: Odonata (Odon: a tooth, toothed flies) Example : Dragonflies, damselflies Characteristics : Characterized by short antennae and inconspicuous Four large net- veined, membranous wings and large head with large protruding eyes and long, slender bodies Mouth parts are well developed chewing type, nymphs are aquatic

133. Contd … 3. Order: Orthoptera (Straight wings) Example : Grasshoppers, crickets Characteristics : High-jumping insects, most of which can use their forewings to produce sounds. Chewing mouth parts The fore wings are modified into tegmina ; hind wings membranous Cerci present.

134. Contd … 4. Order: Phasmatodea (Like a ghost) Example : Walkingsticks Characteristics : Includes both stick-insects, which resemble sticks, and leaf- insects, which look like leaves. Living in dense shrubbery in tropical regions, these insects are primarily vegetarian.

135. Contd … 5. Order: Grylloblattaria Example : Rock crawlers, ice insects Characteristics : Confined to cooler regions, Eyes absent or reduced, ocelli abscent Mouth parts mandibulate Male genitalia asymmetrical Ovipositor well developed

136. Contd … 6. Order: Mantophasmatodea Example : Gladiators Characteristics :

137. Contd … 7. Order: Dermaptera Example : Earwigs Characteristics : Characterized by large, delicate wings Cerci modified into a pincers Omnivorous, nocturanal The common earwig is often found in gardens, where it feeds on wastes.

138. Contd … 7. Order: Plecoptera Example : Stoneflies Characteristics : Ancient group of insects whose early stages occur in water. Adults commonly have delicate, transparent wings and long antennae.

139. Contd … 8. Order: Embioptera Example :Web -spinners Characteristics : Small insects that live communally and are most common in the tropics. Male winged, female wingless Silk glands and spinnig haris on first segment of front tarsus Construct silk-lined tunnels and webs beneath stones and in the soil.

140. Contd … 9. Order: Zoraptera Example : Angel wings Characteristics : Extremely small insects found in warm, humid climates, often in decaying wood. Both winged and wingless forms may occur in the same species.

141. Contd … 10. Order: Isoptera (equal wings) Example : Termites Characteristics : Social, nest-building insects with soft, whitish or colorless bodies and strong biting mouthparts. Also called white ants because of color and social habits Bears a pair of cerci Nest populations range from a few dozen members to hundreds of thousands Only kings and queen reproduce and are winged

142. Contd … 11. Order: Mantodea (like a prophet) Example : Praying mantids Characteristics : Elongated body Raptorial front legs with one or two rows of spines 2 pairs of wings, both of which are used in flight. Although some species have reduced wings and others are wingless Forewings protectively hardened to cover the membranous hind wings when at rest Very mobile triangular shaped head with distinctive ocelli , large compound eyes Short to medium sized  filiform  antennae

143. Contd … 12. Order: B lattodea (Insect avoiding light) Example : Cockroaches Characteristics: Mostly nocturnal insect, with biting mouthparts and legs that are adapted for swift running. The body is oval and dorsoventrally flattened, allowing the animals to hide in narrow spaces, for example under bark or in crevices of trees and rocks.

144. Contd … 13. Order: Homoptera Example: True bugs Characteristics : Characterized by sucking mouthparts used for feeding on plants and animals tissues

145. Contd … 14. Order: Hemiptera (half wings) Example : Bedbugs, aphids, cicadas, True bugs Characteristics : Characterized by sucking mouthparts used for feeding on either plant or animal tissues. ( Homoptera is merged in Hemiptera )

146. Contd … 15. Order: Thysanoptera Example : Thrips Characteristics : Minute insects with a fringe of fine hairs bordering each edge of their wings. Sometimes called thunder-flies because they are particularly active in summer thunderstorms.

147. Contd … 16. Order: Psocoptera Example : Book-louse Characteristics : Barklice , barkflies , or booklice ( Psocoptera ) are minute insects that live hidden away under bark, in leaf litter, or sometimes in your old books. Both adults and larvae can spin silk

148. Contd … 17. Order: Phthiraptera (Louse wings) Example : Chewing lice and sucking lice Characteristics : Small, wingless insects, permanently parasitic on mammals and birds. Minute, wingless insects with mouthparts adapted for chewing and sucking Tiny insects similar to biting lice, except that mouthparts are adapted for sucking. Found in the skin of birds and mammals, they contribute to the spread of some diseases, including typhus fever.

149. ENDOPTERYGOTA (Complex body change during growth) It includes nine orders 1. Order: Coleoptera ( Coleo : Sheath, ptera : wing) Example : Beetles, weevils, fireflies Include 330,000 species Characteristics : Largest order of insects, characterized by hard bodies and chewing mouthparts. Adults are plant feeders and typically have two pairs of wings. Fore wings modified into hard, sclerotized ; elytra where as hind wings are membranous

150. Contd … 2. Order: Neuroptera Example : Lacewings, antlions Include 4000 species Characteristics : Characterized by long antennae, chewing mouthparts, Large leaf like often colored wings, equal size and texture, fine net veined

151. Contd … 3. Order: Hymenoptera (Hymen: membranous, ptera : wing) Example : Bees, wasps, ants, sawflies Include 145,000 species Characteristics : Four wings, hind wings with hooklets called hamuli Some are known for their highly evolved social organization, but most species are nonsocial. All have mouthparts designed for biting, chewing or lapping , eyes well developed and undergo complete metamorphosis. Ovipositor distinct and modified for stinging

152. Contd … 4. Order: Trichoptera Example : Caddisflies Include 5000 species Characteristics : Adults resemble dull moths, but their wings are covered with fine hairs rather than scales. They have soft bodies and poorly developed mouthparts, and they usually live near water.

153. Contd … 5. Order: Lepidoptera ( Lepido : sclae , ptera : wings) Example : Butterflies, moths Include 160,000 species Characteristics : Two pairs of wings, covered with thousands of overlapping scales of varying colors. They have large compound eyes and adults with sucking proboscis, larvae with biting chewing mouthparts. Caterpillars, the larval form, mostly feed on plant leaves.

154. Contd … 6. Order: Siphonaptera (Siphon: a tube, aptera : wing less Example : Fleas Include 1400 species Characteristics : Wingless parasites that suck the blood of mammals or birds. Powerful hind legs enable them to jump from one host to another. Members of this group were responsible for spread of plague

155. Contd … 7. Order: Mecoptera Example : Scorpionflies Include 400 species Characteristics : Oldest group of fully metamorphosing insects. heads with beaklike extensions. Antennae long and filiform Mouthparts biting and chewing type Wings long, narrow subequll and membranous They have slender bodies, abdomen elongate with terminal segments raised like that of scorpion

156. Contd … 8. Order: Strepsiptera Example : Stylopids Include 370 species Characteristics : Minute, beetle-like insects that parasitize other Females live sedentary lives and are visited by males, which fly rapidly with wings that produce a tiny humming noise.

157. Contd … 9. Order: Diptera (Di: two, ptera : wing Example : Mosquitoes, fruit flies, house flies, leaf miners, gall mides Include 85,000 species Characteristics : Known as the true flies, considered the most accomplished fliers of all insects, with an ability to fly backward, forward, and sideways. With few exceptions, they all have a single pair of wings, as well as structures called halters that help them achieve balance in flight.

158. INSECT ORDERS OF ECONOMIC IMPORTANCE

159. 1. THYSANURA : Body relatively flat, tapered and often covered with scales Compound eyes small or absent Antennae long, thread-like, and multi segmented Abdomen with ten complete segments Eleventh abdominal segment elongated to form a median caudal filament Cerci present, nearly as long as median caudal filament Styliform appendages located on abdominal segments 7-9 Domestic species such as silverfish and firebrats may cause extensive damage to household goods.

160. 2. ORTHOPTERA : Grasshoppers / Locusts / Crickets / Katydids The name Orthoptera , derived from the Greek " ortho " meaning straight and " ptera " meaning wing, refers to the parallel-sided structure of the front wings ( tegmina ).   Important characters  1. Antennae filliform 2. Mouthparts mandibulate , hypognathous 3. Pronotum shield like, covering much of thorax 4. Front wings narrow, leathery ( tegmina ); hind wings fan-like 5. Hind legs usually adapted for jumping (hind femur enlarged) 6. Tarsi 3- or 4-segmented 7. Cerci short, unsegmented 8. Immature are structurally similar to adults, developing wing pads often visible on thorax. 9. Orthoptera is generally regarded as a dominant group in most terrestrial habitats. 10. These insects feed on all types of plants and often cause serious economic damage. 11. Swarms of grasshoppers (locusts) regularly appear in parts of Africa, Asia, and North America and destroy crops over wide land areas. 12. Mole crickets are major pests in lawns and golf courses in the southern United States. 13. Several species of field crickets are reared commercially as fish bait.

161. Major Families Acrididae (short-horned grasshoppers and locusts) -- Herbivores. Common in grasslands and prairies. This family includes many pest species such as the twostriped grasshopper ( Melanoplus bivittatus ), the differential grasshopper ( M. differentialis ), the African migratory locust ( Locusta migratoria ), and the desert locust ( Schistocerca gregaria ). Tettigoniidae (long-horned grasshoppers and katydids) -- Herbivores. Females have a long, blade-like ovipositor. Some species are pests of trees and shrubs. Gryllidae (true crickets) -- Herbivores and scavengers. Females have a cylindrical or needle-shaped ovipositor. This family includes the house cricket, Acheta domesticus . Gryllotalpidae (mole crickets) -- The front legs are adapted for digging. Most species feed on the roots of plants, but some are predatory

162. 3. ORDER: HEMIPTERA Hemi- half, Ptera - wings Previously Hemiptera was divided into 2 sub orders Heteroptera and Homoptera . But later on these two suborder become separate and homoptera become different order and the suborder heteroptera being the order hemiptera . Greek word hemi means half and ptera means wings. Characters of hemiptera : The size of the insect varies from <1mm to >100mm. Insect have got piercing and sucking type of mouth parts. They may be winged or wingless. They usually have 4 wings. They may be soft or hard bodied insects. They are brightly or lightly coloured . Many species have glans for secreting odours waxes, scales like coverings. There is hemimetabolous type of development. Basal portion of the front wings of true bus are generally thicken and coloured but membranous overlapping tips are coloured or transparent .

163. Contd …. Hind wing are entirely membranous and hidden under the front wings. Scutellum is usually exposed and triangular in shape. The beak is 3-4 segmented or rostrum is 3-4 segmented. The beak arises from the front of the head and cutves backward to extend along the ventral side of the body. Insect feed on plant sap, seed fungi, fruit juices or blood of insect and other animals including human beings. Many species are plant pest and few species transmit animal diseases but many are of no direct economic importance to human beings Some are predators on some insects Scents glands are present on the side of the thorax and they emit some peculiar odours for self-protection. Most of the species are terrestrial but some common groups are aquatic or semiaquatic .

164. Families of economic importance   Pentatomidae (Stink bugs or shield bugs) Medium to large insects, most common and abundant of bugs that produce disagreeable odour . Broad shield like. Head with lateral margins concealing bases of antennae Antennae usually 5 – segmented. Ocelli almost always present The pronotum broad and shield shaped. Scutellum large triangular sometimes extends posteriorly to the extent of covering the wings entirely. In hemelytron, corium large extending to anal margin. Membrane with many longitudinal veins, arising from a vein which is nearly paralleled to the apical margin of corium. Four pairs of odoriferous glands are present on dorsum of abdomen of the nymphs The eggs are usually barrel shape with spines on the upper end. Eg : Green (stink) bug – Nezara viridula , Red pumpkin bug - Aspongopus janus Cabbage painted bug – Bagrada cruciferarum Lygaeidae Seed bugs or Chinch bugs Small bugs, hard bodied Antennae 4 segmented inserted down on the sides of the head, apical segment is larger Compound eyes and ocelli are well developed 4 to 5 unbranched simple veins in the membrane of hemelytra. Cuneus is lacking, clavus is elongate Metathoracic gland openings are present. In some, the front femora moderately swollen with 2 rows of teeth beneath Coxa rotator, tarsi 3 segmented, pulvulli present Eg . Dusky cotton bug Groundnut pod bug

165. Contd …. 3. Miridae ( Capscidae ) Mirid bugs Medium or small, usually delicate insects Ocelli absent Rostrum is 4 segmented Cuneus is present 5. Empodium is indistinct. Tarsi almost invariably 3 segmented Majority live on plant juices, some prey on small arthropods Eg . Tea mosquito bug - Helopeltis antonii Predator on rice BPH - Cyrtorhinos lividipennis 4. Pyrrhooreidae ( Pyrrhocoreids ), red cotton bugs or cotton strainers They exhibit red and black colorations Ocelli absent More branched veins and ceels present in hemelytra Coxa is rotatory and tarsi 3 segmented with pulvilli Eg.Dysdercus cingulatus – red cotton bug

166. Contd …. Coreidae : Leaf footed bugs Medium to large, long and narrow bugs Antennae 4 segmented sitiuated well upon the sides of the head above a line drawn from the eyes to the base of the beak. Ocelli present. Head narrower, shorter than pronoutm , scutellum smaller. In hemelytra, richly branched veins are present. In most of the species, either or both the hind femora and tibiae may have conspicuous enlargements or leaf like dilations and hence the name leaf footed bugs. Tarsi – 3 segmented pulvilli present. Metathoraccic gland openings present Eg Rice gundhi bug- Leptocorisa oratorius Pod bugs: Clavigralla gibbosa on pulses   6. Pyrrhocoreidae ( Pyrrhocoreids ), red cotton bugs or cotton strainers They exhibit red and black colourations Ocelli absent More branched veins and ceels present in hemelytra Coxa is rotatory and tarsi 3 segmented with pulvilli Eg. Dysdercus cingulatus – red cotton bug

167. 4. ORDER: HOMOPTERA. Homo: Alike; Pteron : Wings (uniform wings) Jassids , Aphids, mealy bugs, whiteflies etc Important characters This order contains a large and diversified group of insects and is closely related to the hemiptera . 1. These are minute to small insects and are distributed widely 2. Head is deflexed and not generally constricted behind to form a neck. 3. Compound eyes well developed, ocelli absent in apterous form but 2 to 3 in winged forms 4. Antennae well developed and usually 3 to 10 segmented  5. Mouth parts piercing and sucking type, stylets often exceedingly long, retractile, rostrum arising from the back of the head, in some cases appearing to arise between anterior coxae . In some adults like male coccids the mouth parts are vestigial or absent 6. Thoracic segments generally fused together and not distinguishable from abdomen in wingless forms. Pronotum small and collar like. 7. Winged or wingless when winged the four wings are uniform in consistency and the wings are held roof like over the body at rest. Alary polymorphism is prevalent. In male coccids only one pair i.e. forewings are present. 8. Wax glands or honey tubes usually well developed in most of the members of this order. 9. In most of the species, the life history is very complex involving sexual and parthenogenetic generations winged and wingless individuals. 10. Usually undergo simple metamorphosis. In some species, the last nymphal instar is quiescent and pupalike .

168. Families of economic importance 1. Cicadellidae : ( Jassidae ): Jassids or leaf hoppers Slender, usually tapering, posteriorly , wedge shaped insects usually rest in a position ready for jumping. When disturbed they leap often several feet. Antennae minute, bristle like, 3 segmented One or two rows of small spines are present on hind tibia which is most important feature Both young ones and adults have the characteristic habit of running sideward or diagonally These are very important vectors of viral diseases. Ovipositor well developed and adopted for lacerating plant tissues for egg laying. Many excrete honeydew through anus. Forewings are somewhat thickened and often brightly coloured Anal veins 1A and 2A do not unite to form ‘Y’ shaped vein. Eg : Cotton leafhopper - Amrasca biguttula biguttula Paddy leafhopper - Nephotettix virescens – Mango hoppers - Amritodes atkinsoni,Ideoscopus clypealis 2. Delphacide Plant hoppers This is the largest family among the plant hoppers Most of the species are small with reduced wings The characteristic feature of this family is the presence of large mobile apical spur on hind tibiae · Costal cell is absent in the winged forms · Alary polymorphism is very common winged, wingless and brachypterous ·Forms occur in the some species. Eg Brown plant hopper of paddy (BPH)- Nilaparvata lugens · White backed plant hopper on rice (WBPH) - Sogatella furcifera

169. Contd …. 3. Aphididae Aphids or plant lice This family constitute a large group of small soft bodied, pear shaped, fragile phytophagous insects that are frequently found in large numbers sucking the sap from various parts of plants Antennae fairly long Rostrum usually long and well developed The characteristic feature of aphids is the presence of a pair of cornicles on the dorsal surface of 5th or 6th abdominal segments (It is believed that they produce waxy substances)   Winged / Wingless. Alary polymorphism is prevalent. When winged, hind wings are much smaller with fewer veins. At rest the wings are generally held vertically above the body. Tarsus – 3 segmented with a pair of claws Nine pairs of lateral spiracles present Excrete honeydew through anus (honey dew consists of excess sap, excess sugars and waste materials) to which ants are attracted, Associated phenomenon in reproduction are parthenogenesis, oviparity and viviparity Occurrence of alternation of generations. The sexes are unequally developed, males often being rare. Eg : Myzus persicae – Tobacco aphid, Aphis gossypi – Cotton aphid, Aphis craccivora – Groundnut aphid

170. Contd …. Pseudococcidae Mealy bugs Females are wingless, elongate oval with distinct segmentation. Body covered with powdery wax or filamentous waxy secreations . Legs well developed. No instar is sessile. All the insect stages are able to move because of legs Eggs are placed in a loose cottony waxy material Eg : Brinjal mealy bug – Planococcus insolitus Citrus mealy bug - Planococcus citri Sugarcane mealy bug - Saccharicoccus sacchari   5. Coccidae Scale insects (Soft scales) The females in this group are flattened, elongate oval insects with obscure segmentation and hard smooth exoskeleton or covered with wax or tough scales. They are wingless, legs present or absent and the antennae absent or much reduced. Males are active, 1st pair of wings well developed, 2nd pair reduced to halters. Tarsus if present 1 – segmented with a single claw. Metamorphosis complex. 1st instar nymph has legs & antennae and active known as crawlers after 1st moult , become sessile a waxy or scale like covering is secreted. In males last instar preceeding adult is queicent and called pupa. Females have one less instar than males. Oviparous, ovoviviparous Excrete honey dew like aphids Eg : Pulvinaria psidi – Guava scale, Icerya purchasi - cottony cushion scale 6. Aleurodidae E.g. White flies  E.g.: Sugarcane whitefly – Aleurolobus barodensis Cotton whitefly - Bemisia tabaci Castor whitefly - Trialeurodes

171. Difference between Hemiptera and Homoptera Sn He m i pt er a (True bugs) Ho m o p te r a (Aphids, Jassids , mealy bugs, whiteflies) 1 P ronotum usual l y l a r g e P ronotum s m a ll a nd c ol l a r like 2 Gul a r re g ion pr e s e nt a nd it i s s c le r ot iz e d (the ma x i l la r y plat e s m ee t a nd f u se v e nt r a l l y to fo r m g ula ) Gul a r re g ion a b s e nt or v e r y small a nd memb ra nous 3 F orewin g s h e me l y t ra F orewin g s unif o rm in c o nsi s ten c y 4 W in g s fold f lat ov e r the bo d y a t r e st W in g s h e ld roof l i ke ov e r the bo d y 5 B ea k or rostr u m a rise fr om the f r ont p a rt of the h ea d a nd b a se of the rostr u m not t ou c hing a nt e rior c o x a e B ea k o r rostr u m a rise f r o m the post e rior p a rt of the h ea d a nd b a s e of rostr u m e x tending b e tw ee n a nte r ior c o x ae 6 T a rsi – 3 s e g men t e d a ntenn a e 4 - 5 s e g men t e d, odori fe rous g lands a re pr e s e nt T a rsi 1 - 3 s e g ment e d a ntenna 3 - 10 s e g men t e d, w a x g lands a re pr e s e nt.

172. 5. COLEOPTERA Typical characteristics: Hard Exoskeleton and hardened pair of wings called elytra which covers the abdomen and the flight wings. Beetles comprise the largest order of insects with over 300,000 species forming about 40 percent of the known insects. Beetles have thickened front wings (elytra) that are soft, leathery, or hard and brittle. The elytra usually meet in the straight line along the middle of the longer, folded, membranous hind wings. Some beetles have short elytra and or hind wings or are wingless. Most beetles use only the hind wings for the flight; the elytra are raised to allow for hind wing movement. The pronotum is generally distinct whereas the mesonotum and the metanotum are hidden beneath the elytra. The mouth parts of the adults and most larvas are adopted for chewing. Some predatory larvae are able to suck body fluid of prey.

173. Contd …. Larvae have a holometabolous type of development. Beetles sizes vary from less than 1mm to over 200mm in length and up to 75mm in width (e.g. tropical rhinoceros and goliath beetles). Body shape varies from round to slender, and flattened to stout or cylindrical. Some adults have long and slender snout, horns, or tubercles on the head, extremely long antennae, greatly enlarged mandibles or other r diverse features. The body and elytra surface may be smooth or rough, brightly colored or dull. Many beetles produced sounds by rubbing body parts together (e.g., femur of the margin of the elytron ; head rubbed against the fronted margin of the prothorax ) Some members of the Lampyridae , Phenogodidae , Drilidae and Elateridae emit light (bioluminescence from special organs. Certain beetles in the families: Staphylinidae , Pselaphidae , Scydmaenidae , and others live in the nests of ants and termites.

174. Contd …. Beetles are primarily plant feeders and scavengers, although a significant number are predators of insects and other small invertebrates and a few are parasites. The plant feeding habit of adult and larvae have made many beetles serious pests of agricultural crops and forests. Some beetles also feed on museum specimens, clothes and stored food .a few species transmit bacterial and fungal diseases to plants. Life cycles vary from several weeks in warm climates to four or more years in cool climates. Wood and root boring beetles usually have longer life cycles than leaf feeding species. Eggs are usually deposited in an area suitable for larval development the larva sometimes called grubs, typically molt three to five times. The immobile pupa is soft, pale and resembles the adult.

175. Economically important families 1. Carabidae : ground beetles 2. Cicindellidae - Tiger beetles Cicindela oregona : 12-14mm; green or blue; white or dull yellow markings; long hairs near inner edge of eyes; labrum short; punctate elytra. Cicindela punctulata : 10-13mm; brownish black or slightly green either bronze sheen; row of small greenish or bluish depression on elytra; small white markings present or absent along elytral margins. 3. Scarabaeidae - Scarab Beetles Common name : scarab, June, and dung beetles The body sizes ranges from 2-70mm in length. Some are metallic, other are hairy ventrally. Scarabs are generally attracted to light. The stout larvae have a curved body that is often wrinkled and the thoracic legs are well developed. Elateridae - Click beetle Lampyridae - Fireflies

176. Contd …. 6. Dermestidae - Dermestid beetles 7. Coccinellidae - Lady beetles Common name : ladybird beetles, ladybugs, lady beetles They are broadly oval. Convex insects that often are brightly colored. Some lady beetles are similar to the leaf beetles ( Chrysomelidae ) but differ by having three distinct tarsal segments instead of appearing to have four as do leaf beetles. Most of the insect are of predators of aphids, scales. 8. Meloidae - Blister beetle They are elongated beetles with a prothorax that is often narrow than the head and sometimes neck like. The wings and body are soft and frequently the tip of the abdomen in exposed. Common specie Banded blister beetle: Mylabris phylerata 9. Chrysomelidae - Leaf beetles

177. Contd.. 16. Cerambycidae - Long horned beetles or Round headed wood borers They are usually medium to large, elongated and cylindrical beetles with antennae over half the body length. The eyes are notched and many species are brightly colored. Some smaller Cerambycids resemble the leaf beetles ( Chrysomelidae ) but the leaf beetles are smaller and the antennae are less than half the body length. Common species Mango stem borer ( Batocera rufomaculata ). 17. Bruchidae - Pulse beetles These are oval or egg-shaped beetles are generally less than 5 mm long and their elytra do not cover the tip of the abdomen. The head is extended into a short, broad snout and the antennae may be clubbed, serrate, or pectinate . Common species Bruchus pisorum (pea weevil), Callosobruchus maculates, C. chinensis 18. Curculionidae - Weevils or snout beetles Well developed and downward curved snout. The antennae is elbowed and clubbed and the first segment often fits into a groove in the side of the snout. Common species Banana rhizome weevil, Banana stem weevil, Rice weevil ( Sitophilus oryzae ) Maize weevil ( Sitotrora cerealella ), Gray weevil

178. 6. ORDER : DIPTERA Important characters Ø Flies are characterized by a single pair of membranous wings attached to an enlarged mesothorax . Ø The hind wings on the metathorax are reduced to a pair of knoblike appendages. Ø The halter, which help to balance the insects. Ø Flies range in size less than 1mm in length (midge) to 75 mm (tropical robber flies). Ø The compound eyes are often large; in mangy groups the expanded eyes of males meet on top of the head whereas they do not in females. Ø Most adult flies have sucking mouth parts that are modified for piercing, lapping or sponging the mouth parts are nonfunctional in some species. Ø Food consists chiefly of nectar but numerous feed on fruit juice, plant saps. Ø Fly larvae are usually legless and have either a distinct or greatly reduced head. The latter types are maggots.

179. Economically important families 1) Culicidae The presence of scales on the wings and body and the long proboscis help to identify mosquitoes. Male are prominent plumose antennae. Females feed on nectar as well as blood; the majority of species feed on animals other than humans. Mosquitos ’ larvae and pupae are aquatic and occur in a variety of habitats depending on the particular species. Common species Ades , Anopheles, Culex 2) Tabanidae - Deer and horse flies Common species Tabanus atratus , Tabanus liineala , Chrysops callidus 3) Asilidae - Robber flies They have a long abdomen that tapers posteriorly , a bearded face and concavity on top of the head. 4) Syrphidae – Flower flies, Syrphid fly Common species Syrphus opinator Syrphus ribesii

180. Contd …. 5. Tephretidae / Trypetidae - Fruit flies These are small to medium sized flies have banded or spotted wings and varied body colors. Many species slowly move their wings up and down while resting. Common species: Mango fruit fly ( Dacus sp. ). Citrus fruit fly, cucurbit fruit fly 6. Drosophilidae - Vinegar flies They are 3-4 mm long and generally yellowish. Adult are very common around ripe and fermenting fruit and also occur on decaying vegetation. Common species Drosophila melanogater

181. Contd ….. 9. Agromyzidae - Leafminers The tiny to small black or yellowish flies in this family are common on vegetation but easily overlooked because of their small size. Larvae are chiefly leaf miners and often make a narrow winding mine that widens towards one end as the larva grows. Common species Phytomyza sp . 10. Muscidae - House Flies, Stable Flies and Allies Common species Musca domestica , Musca autumnalis , Muscina stabulans 11. Calliforidae - Flesh flies 12. Tachinidae - Tachinids 13. Babilionidae - Marsh flies

182. 7. ORDER: HYMENOPTERA Hymeno - Membrane and Ptera -Wings. Bees, Wasps, Ants, Sawflies, Horntails etc. Relatively very few species are considered as pests and are of conspicuous economic importance to crops. Wasp, bees and some amts are well known for their stings. Some Hymenopterans are major pollinators such as honey bees and others are important biological control agents of other insects. The order includes more than 70 families and 110000 spp. all over the world. The important characters of this order are: Sizes range from 0.20 mm to 65 mm in length. Mouth parts are chewing or reduced in larvae but chewing or chewing-lapping in adults. Antennal are fillform and geniculate etc. Compound eyes are large but absent in ants. Legs are long with five segmented tarsi. Two pairs of long narrow membranous wings with fused venation are absent. Hamuli or hooks represent on hind-wings of all winged forms. The ovipositor may be modified into a sting. Some species are highly social and have caste differences. Larvae are either caterpillar-like or they are called “grubs”. Larvae herbivorous or parasitic to scavenger. Metamorphosis is complete. Most species have constriction between thorax and abdomen. Wingless workers of ants and sawflies are exceptions.

183. Economic important families 1. Apidae (Honey bees) Hind tibia without spur and eyes hairy. Hind metatarsus modified as a pollen basket on worker bees. Caste-system with non-reproductive workers and reproduction queens and drones. Example: Honey bee, Apis indica L. Very important pollinator of many plants. Honey and beeswax are useful items produced by t hem. Bee venom sometimes used in traction illness of joints in man as at arthritis, for making one pound of honey, one bee has to make flight equivalent to twice around the world. 2. Bombidae ( Bumble Bees- Bhanwara ) Hind tibia with spurs and the first segment of hind tarsus is flattened. Examples: Bumble bee, locally known as Bhanwara . Very important family of plant pollinators. 3. Formicidae (Ants) Geniculate antennae, usually wingless, drones and queens winged in mating season, workers always wingless and non-reproductive, and the ant make nests with the leaves and several leaves are tied with silken threads. 4. Tenthredinidae (sawflies) Example: mustard sawfly, Athalia proxima lugens . The larvae feed on the leaves of mustard and sometimes other cruciferous crops.

184. Contd …. 5. Trichogrammatidae (insect egg parasites especially lepidpterous insects). Example: Trichogramma sp; egg parasite of various shoot and stemborers . Natural and biological control agents as egg parasites of pest insects. Man can rear and release insects t o control pest insects in the field. 6. Ichneumonidae Example: Xanthopimpla predator, pupal parasite of chilo partellus . The members of this family are mostly parasitic on caterpillars and other insect larvae and pupae.   7. Chalcididae ( chalcids ) Example: Seed Chalcids . The seed chalcids infest seeds causing their destruction. Some species of chalcids are helpful as natural control agents as egg parasite of some other insects. 8. Braconidae ( Braconids ) Examples: Apanteles spp.; a larvae parasite of Pieris brassicae . 9. Vespidae Examples: common wasps

185. 8. ORDER: LEPIDOPTERA The word “Lepidoptera” is derived from the word, “ Lepis ” means “scale” and “ ptera ” means “wing”. There are scaly wings in this order’s insects. Examples: Butterfly, moths, skippers (neither butterfly nor moth). Adult Lepidopterans are small to large insects. Having 200-300 mm normally wing span (Spread). They have minute and powder like scales that covers the wings and body of most species. Lepidopterans have usually 4 large wings. Although, some female moth are short- winged or wingless. Examples: Bagworm. Compound eyes are large. Antennae are long. Moths: Filamentous or thread like antennae Butterflies: Clavate shaped. Skippers: having hooks like at the end. Mouthparts are generally reduced but maxilla and labial palp are extended. The proboscis is extended to suck up the liquid food and coiled when not in use. Some moth have not proboscis. Certain moths have membranous auditory-organs on mesothorax or abdomen. Vision is good. Many individuals respond to motion, flower shapes, wing pattern, blue- violet and ultraviolet light.

186. Contd …. Immature or caterpillars have holometabolous type of development (complete metamorphosis). Males often have patches of specialized scent-scales, which emit pheromones involved in mating or it may fasten itself with silk to the vegetation Adult lepidopterans feed primarily on flower-nectar and are good pollinators. Females usually deposits eggs in masses on food plants or disperse them on or near the plant. Larvae or caterpillars have biting and chewing types of mouth-parts. Most larvae have prolegs ( prolegs are fleshy). The prolegs vary from two to five pairs or none. Caterpillars head is usually distinct from the rest of the body and has an inverted ‘Y’ shaped suture on the face. There may be 0-6 pairs of ocelli (stemmata). The body of caterpillars may naked or have a covering of hairs (setae) of varying density. Nearly all caterpillars are plant feeder and most are restricted to one or a small group of plant feed. Many larvae are serious pests feeding on or inside foliage, fruit, stems, roots, flowers, wood, stored grain and flour, bee wax and fabric. A few caterpillars feed on aphids, leafhoppers, mealy bugs, scales and immature ants. Larval development takes two moulds, but some takes even three. Silk may be produced by silk gland situated in the head of larvae. The silken threads are used by the larvae to adhere to surfaces to construct cites, nests, shelters and to form cocoon just before the larvae molts into the pupal stage. Example: Silk-worm. Before pupation the mature larva seeks shelter in soil, debris, under bark, inside foliage or it may fasten itself with silk to the vegetation

187. Difference between moths and butterflies Chara c te r s M oth B u t ter f l i e s B e h a vi o rs No c turn a l Diur na l Ant e nn a e P ec t i n a te , plumose Clav a te O ce l l i P r e s e nt Abs e nt M a ndib l e s P r e s e nt Abs e nt L a b rum P r e s e nt Abs e nt F r e nulum P r e s e nt Abs e nt W in g s a t r e st H e ld roof l i ke ov e r bo d y F olded v e rti ca l l y u p w a rd Abdom e n L ar g e a nd stout Compa ra t i v e l y small a nd slend e r P upa Obt ec t pupa with in a c o c oon Obt ec t pupa without c o c oon. I t is a n a k e d pupa bri g ht c olour e d a nd support e d b y a si l k e n gird l e s, ca l l e d a c h r y s a l i s. Olf a c to r y s e nse S trong Not strong Moth hov e rs on flo we rs B ut t e r f l y land on a flo w e rs

188. Economically important families 1. Pieridae Cabbage or white or sulfur or orange tip butterfly e.g. Pieris brassicae nepalensis . Larvae feed on leaves of Cole-crops. Other example: Pieris canidia . 2. Papilionidae Examples: Papilio demoleus (lemon butterfly). Brightly colored, dark-blue, black, or dark with bright yellow or orange red green marks on the body of the insects. They are serious pest of citrus fruits. Larvae feed on leaves. Hind wing is extended into a tail-like projection. Swallow tailed butterfly. 3. Nymphalidae Brush footed or four footed butterflies. Examples : Nymphalis spp.; Peacock pansy. 4. Hesperiidae Skipper - pest of several crops. Antennae widely separated at base, clubbed, hooked at the tip. Head is as quite as or even wider- than the thorax. Hold wings at different angles. E.g. Pelopedas mathias (Rice-skipper). 5. Danaidae Milk-weed butterfly or Monarch butterfly (Plain tiger). Larvae of this insect feed on milk fluid of different plants. Examples: Danaus plexippus .

189. Contd …. 6. Satyridae : Rice green horned caterpillar Example : Melanitis leda ismene (Rice green horned caterpillar) Feed on leaves of rice. Moths ( Heterocera ) 1. Noctuidae Example: Noctuid moths. Largest family, about 4000 spp., dull colored, front margin or wings are quite straight, forewing is somewhat narrower as compared to hind wings, and few species are crop pests. E.g. Spodoptera litura (Tobacco Caterpillar) Spodoptera exigua ; Helicoverpa armigera (Gram pod borer) Agrotis ipsilon (Cutworm) These insects feed on several types of crop plants. Cutworm cut the succulent stem of plants from the ground level. The plants affected by this worm are cruciferous vegetables, solanaceous crops and others. 2. Pyralidae Borers, Pyralid moths. Palpi projected towards foreside forming a beak like structure Examples: Maize stem borer: Chilo partellus . Rice Caseworm: Numphula dipunctalis ; Rice stem borer: Scirpophaga incertulus . Rice leaf roller: Cnaphalocrosis medinalis . 3. Plutellidae : Example: Diamond back-moth. Plutella Xylostella Xylostella maculipenis . Larvae damage the plants. Serious pest on Crucifers

190. Contd …. 4. Lasiocampidae Example: Tent caterpillars and Lappet moths. Tent caterpillar builds silken nests in the crotches of cherry, peach, plum and other trees like apple. 5. Bombycidae : Silk moth, Bombyx mori

191. Life Cycle of Honey Bee ( Apis indica ) Life cycle of honeybee is very informative to understand their social behavior, communication and developmental aspects. Honey and wax are valuable products of0 honeybees. Besides, they also help in pollination of various crops. Thus, it is necessary to learn about bee colony and their development Life cycle : Honey bees are holometabolous insects that have four different stages of development. Eggs : Queen starts laying three to four days after mating. She lays as many as 2000 eggs in a day. Eggs are creamy white in color and banana shaped. Eggs hatch in 3 days. Larvae : Known as grubs, they have no legs and eyes. All grubs feed on 'royal jelly' for the first 3 days. Thereafter, workers and drones are given 'bee bread'. This stage remains 7 days for drone, 5 days for queen and worker. Pupae : On about 9 th day, cells containing grubs are sealed with a wax cap. Pupal stage passes inside the sealed chamber. Grub secretes a thin silken cocoon around itself. This stage lasts 8 days for queen, 13 days for worker, and 14 days for drone.

192. Life Cycle of Honey Bee ( Apis indica ) Adults : They come out from the cell by making hole through the cap. They are differentiated into three different castes. Queen: She is bigger in size than drones and workers. Queen is the only fertile female in a hive, hatched form fertile eggs. Her grub stage is specially fed on royal jelly. Her duty is to lay eggs and regenerate the colony. Drones: They are intermediate in size. They develop parthenogenetically from the unfertilized eggs. They fertilize queen and may sometimes regulate the temperature inside the hive. Workers: They are the smallest members of the colony, coming out of fertile eggs, but unable to reproduce. Workers possess various structures in their legs such as comb, pollen press and pollen basket. They perform various activities, like secretion of wax and comb foundation, cleaning of cells in which queen lays eggs, feeding the queen and grubs, collecting pollen and nectar, producing honey, regulating temperature and guarding hive against robber bees.

193. Life Cycle of Mulberry Silkworm ( Bombyx mori Linnaeus) Silk is a very valuable commodity. The best quality of silk is obtained from the mulberry silkworm, Bombyx mori . This insect passes through a complete metamorphosis. The study of life cycle is very important in order to be familiar with its various stages of development so that proper care and feeding can be done during the larval instars, for higher and better quality of cocoon production. Life cycle: Female lays 300-400 eggs on mulberry leaves or artificially prepared butter cups. Eggs are oval in shape and creamy white in color. They hatch in 9-11 days. Proper temperature and humidity should be maintained for good hatching. Larvae (Caterpillars) : Newly hatched larvae are black or dark brown in color and become smoother and lighter during different succeeding instars. There are five larval instars first two instars are as young worms and rest three instars are called grown up warms. Larvae after last moult . raise their head and search a shelter for resting. They secrete silken thread and cover themselves. Larval stage lasts for 18-24 days. Pupae : This is the resting stage or inactive stage in which pupae remain covered in the silken cocoon. It lasts for 11-14 days. Adults: Adults come out by making a small hole through the cocoon. They do not eat during their short life span.

194. Life Cycle of Lac Insect ( Kerria lacca ) Lac is a recinous secretion of a tiny lac insect. It has been used for various preparations such as surface coating, mirror backing, printing drawing, hair liquers , gramophone records, electric goods etc. Life cycle study of a lac insect provides information on their developmental stages, which could be very useful for inoculation, harvest and other management aspects. Life Cycle: This insect passes through a gradual metamorphosis and has three different stages: Eggs: Oviposition starts just after mating. Eggs are laid in cells inside in crustation . A female lays 300-1000 eggs and dies soon after oviposition . Eggs start hatching within a few hours. Nymphs: They thrust hair like proboscis up to the phloem of host plants and derive their nutrition. Once settled, they do not move about. Nymphs have 3 moults . After first moult they loose their antennae, legs and eyes. These appendages are again developed after second moult . Nymphs are encaged in their own secretion and cell size increases with the increase in the growth of lac insect. Nymphal stage lasts for about two months. Adults: A short time after emergence, mating takes place and female continues laying eggs.

195. Entomology and Pest Management ( Seventh Edition) Lerry P Pedigo Marlin E Rice