Insect Order : apterygota

wingless insects

1. Order : Apterygota Prepared by Dr. S. Sumaiya

2. CLASSIFICATION OF CLASS INSECTA UPTO ORDERS Insect is a six legged arthropod Taxonomist A.D. Imms proposed a classification of insect Phylum : Arthropoda (with several classes) Class: Insecta ( Hexapoda ) Characters of class Insecta 1. Body is divided into three regions 2. In head a pair of antenna and a pair of compound eyes are usually present. 3. Thorax is the centre of locomotion with, 3 pairs of five jointed legs and two pairs of wings. 4. Excretion is mainly through malpighian tubules. 5. Tracheal system of respiration well developed. 6. Brain is divided into protocerebrum , deutocerebrum and tritocerebrum .

3. Class: Insecta The class Insecta has two subclasses viz., Apterygota and Pterygota .

4. Apterygota The subclass Apterygota has 4 orders namely 1. Thysanura Silverfish ( Thysan -fringed, Ura -tail ) 2. Collembola Springtail or snowflea ( coll -glue; embol -peg) 3 . Protura Proturans or Telsontail ( Pro-first, Ura -tail) 4 . Diplura Diplurans or Japygids (Di-two; Ura -tail)

5. Thysanura Body is elongate and flattened. Body is glistening and clothed with scales . Compound eyes are present or absent. Antennae is long, filiform and multisegmented . Mouthparts are ecotognathous , biting type. They are primarily wingless insects. Abdomen is 11 segmented. Styli are belived to be reduced abdominal legs. Female has elongate jointed ovipositor. Abdomen at its tip carries a pair of elongate many segmented cerci and a median caudal filament. Insemination is indirect . Metamorphosis is absent. Moulting continues even after attaining sexual maturity.

6. Collembola They are minute insects. Body is globose or tubular. Compound eyes are absent. Antenna is four segmented. Mouthparts are entognathous biting type and found within a pouch . Tibia is fused with tarsus to form tibio -tarsus. They are primarily wingless. Abdomen is six segmented with there medially situated pregenital appendages. Malpighian tubules, tracheal system and metamorphosis usually absent .

7. Collembola Ventral tube or Collophore or Glue peg: It is a bilobed adhesive organ found on the first abdominal sternite . It is beleived to be associated with respiration , adhesion and water absorption. Hamula or Tenaculum or Retinaculum: It is present on the third abdominal sternite . It consists of a fused basal piece, corpus and free distal part called rami. It holds the furcula . Furcula or Springing organ: It consists of a basal manubrium, paried dens and distal claws called mucro . It is held under tension beneath the abdomen by retinaculum when at rest.

8. Protura Proturans do not have eyes or antennae . Head is conical and all mouthparts enclosed within the head capsule   The front pair of legs are usually held in front of the body and apparently serve as sense organs.  Newly hatched proturans have nine abdominal segments.  Each time they molt, another segment is added near the end of the abdomen until they are fully grown (and sexually mature) with 12 abdominal segments - Anamorphosis Additional molts may occur during adulthood, but the body does not grow any longer.

9. Diplura S mall – most are 2-5 mm, or 0.08-0.2 inches long, but a few species can reach 5 cm or 2 inches in length S oft , pale-colored body Eyeless Wingless L ong antennae that look like strings of beads Two cerci, which may be long and thread-like, or short and pincer-like N ymphs and adults nearly indistinguishable