The document summarizes body segmentation and external genitalia in insects. It describes how an insect's body is divided into three segments - the head, thorax, and abdomen. Each segment has distinct features - the head contains antennae, eyes, and mouthparts, the thorax contains three pairs of legs and sometimes wings, and the abdomen contains the digestive and reproductive organs. External genitalia like the ovipositor are also discussed, which can take different forms like needle-like, sword-like, or modified for stinging.

2. SUBMITTED BY SUBMITTED TO
Chanchala Meher M.K.Singh
ASSIGNMENT ON BODY SEGMENTATION,
GENITALIA & THEIR MODIFICATION

3. An insect's body is divided into three segments:
head, thorax, and abdomen.
Some of the segments are more or less united in
to groups forming distinct trunk sections or
tagmata. This type of grouping of segments in to
body regions is called tagmosis and each region
is called tagmata.
Body Segmentation in Insects

4. Cont…
 On the head is a pair of feelers, or
antennae , compound eye , simple eyes,
mouth parts present.
 •On thorax 2 pairs wings and 3 pairs legs
are present.
 The abdomen, or end segment of the
body, is where food is digested and
excreted and where the reproductive
organs are located.

5. Cont..

6. Cont…

7. Cont..
 Each body segment is formed into a ring like
structure by the fusion of dorsal tergum,
ventral sternum and lateral pleuron. (Picture
below is Transverse section of Insect
Thorax).

8. APPENDAGES OF INSECT:-
 Head Appendages
 Thoracic Appendages
 Abdomenal Appendages
HEAD – 1st segment of insect.
 The head is the feeding and sensory
centre.
 Head consists of SIX fused segments.
 It bears the antennae, eyes, and
mouthparts.

9. FRONT & LATERAL VIEW OF INSECT HEAD

10. Antennae-By means of the antennae, the insect detects
odours( olfactory function) and experiences the sense of
touch.

11. Insect Compound Eye-
The head contain compound eyes and simple eyes
(ocelli). Compound eyes are formed of a large number
of individual facets or lenses (ommatidia)

12. Mouth parts-The mouthparts include a labrum or
upper lip; a pair of principal jaws or mandibles; a pair of
accessory jaws or maxillae and a labium or lower lip, &
fleshy epipharynx and hypopharynx..

13. THORAX- 2 segment of insect.
 • An insect thorax is divided into three
parts: the prothorax (pro=first),
mesothorax (meso=middle), and
metathorax (Meta=last).
 • Each segment consists of hardened
plates, or sclerites. Dorsal sclerites are
called nota (singular notum), lateral
sclerites are called pleura (singular
pleuron), and ventral sclerites are called

14. Cont….
 Each thoracic segment contains one pair
of legs.
 • Wings are found only on the meso- and
metathoracic segments, and are together
called as pterothorax.
 Prothorax never bears wings and varies
in size.

15. Insect leg-It is ventro -lateral
extension of insect exoskeleton

16. Insect wing-It is the dorso- lateral
extension of insect exoskeleton

17. ABDOMEN: 3rd segment / largest segmnt of insect.
 In typical insect, abdomen consists of eleven
segments.
 The abdomen contains the reproductive organs
and the majority of the organ systems.
 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.

18. Cont…
 Reproductive structures are located on
the 9th segment in males and on the 8th
and 9th abdominal segments in females
 Abdominal segments are divided in to
three categories.
 01-07 segments pre genital segments
 08-09 segments genital segments
 10-11 segments post genital segments

19. (FEMALE EXTERNAL GENITALIA, COPULATORY
OPENINGS AND OVIPOSITOR).

20. .
 The ovipositor is the egg-laying device found only in
female insects. In some insects, the ovipositor is
highly modified and conspicuous..

21. Parasitic wasps (order Hymenoptera) use their
ovipositors to
insert eggs or small larvae into or onto a host.
Needle-like ovipositor on parasitic Ichneumonid
Female, wasp (order Hymenoptera)

22. Needle-like ovipositor on : Field cricket, Gryllus spp

23. Long & sward like ovipositor in long horned grass
hopper.

24. Short & horny ovipositor in short horned
grasshopper.

25. Ovipositor modified to sting in worker
honey bee.

26. Pseudoovipositor – House fly & fruit fly , last
abdominal segment are telescopic and aid in
ovipositon