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
 Small – 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
 Soft, pale-colored body
 Eyeless
 Wingless
 Long antennae that look like strings of beads
 Two cerci, which may be long and thread-like, or short and pincer-like
 Nymphs and adults nearly indistinguishable