the ppt provide all the notes about insect anatomy

1. Course No. – ENTO-121
TITLE-FUNDAMENTALS OF
ENTOMOLOGY
Dr. Anita Sharma
Asstt. Professor (Entomology)

2. Entomology- Greek word (Entomon =
Insect; Logos = Study) It is the branch of
zoology or biological science that deals
with the study of insects.
INTRODUCTION
Insect:- The insects are the tracheate
arthropods in which the body is divided in
to head, thorax and abdomen possessing
• 2 pairs of wings.
• 3 pairs of working legs.
• 1 pair of antennae.
• Segmented body.
• Having complete and incomplete
metamorphosis.

3. • Insect is Greek word = Cut in pieces or
segmented.
• Insects belong to the Phylum Arthropoda (Artho=
jointed, Poda= Legs) which is the biggest phylum
of kingdom Animalia. More than three quarters
of the animals on earth are arthropods, and most
of these are insects.
• Kingdom Animalia is classified into twelve phyla.
INTRODUCTION

4. • Study and use of insects in crime investigations is known
as Forensic Entomology.
• Study of insects related to live stock and veterinary
animals is known as Veterinary Entomology.
• Study of insects in relation to Human beings is known as
Medical Entomology.
• Study of insects in relation to Agriculture is known as
Agriculture Entomology
Branches of Entomology

5. Topic -1, HISTORY OF ENTOMOLOGY IN INDIA
 Aristotle (384-322 B.C.)– Father of biological classification. First person grouped insects in
winged and wing less groups. He gave the terms like Coleoptera and Diptera.
 Carolus Linnaeus (1758)– Father of Taxonomy.
 William Kirby considered as “Founder of Entomology” because of his significant role in
Entomology in the world. He published a book “An Introduction to Entomology” (1815-
1826).
 Snodgrass R. E. (1875)– referred as a Father of Insect Morphology. He wrote book -
Principles of Insect Morphology.
 Mithan Lal Runwal (1908)– Outstanding work on termites/ white ants. Contributions to
ecology, embryology and locust.
 1940 - Dr. T.V. Ramakrishna Ayyar published the book "Handbook of Economic Entomology"
which met the long felt need of the students of Agriculture and agricultural scientists as well
and also known as “Father of Indian Entomology”.
 Dr.S.Pradhan (1969) - Wrote a "Insect Pests of Crops" and Father of Modern Applied
Entomology in India.

6. History of Entomology in India
 1758 - 10th edition of Systema Naturae by Linnaeus with only 12 Indian insects which was
the earliest record.
 1779 - Dr. J.G. Koenig - Medical Officer initiated the work on Indian insects on scientific
lines. He also published a special account of the termites of Thanjavur District.
 1782 - Dr. Kerr Published on account of lac insect.
1785 - Asiatic Society of Bengal started in Calcutta and many papers were published in the
Societys publications.
1790 - Roxburgh (Botanist) published a detailed account of lac insect.
1791 - Dr. J. Anderson issued a monograph on Cochineal scale insects
1800 - Buchanan (Traveller) wrote on the cultivation of lac in India and on sericulture in
some parts of South India. Denovan published Natural History of Insects which was the first
contribution on the insects of Asia and was revised in 1842 by West Wood.
1875 - Foundation of the Indian Museum at Calcutta

7.  1883 - Bombay Natural History Society was started. After the foundation of these two
organisations scientific studies received greater attention in India. Numerous contributions
of Indian insects were published in the Journal of the Bombay Natural History.
 1893 - Rothney published on Indian Ants (earliest record of biological pest control in
India) i.e. White ants attach on stationary items was kept free by red ants.
1897 - Bingham's issued volumes on "Hymenoptera' (Ants, bees and wasps). Since than
volumes on other groups of insects like Coleoptera (beetles), Hemiptera (bugs), Odonata
(dragenfly and damselfly), etc., were published.
1889 - Indian Museum, Calcutta published the Indian Museum Notes in five volumes.
1901 - (Lionel de Nicevelle) posting of the first entomologist to the Government of India.
1905 - Establishment of Imperial Agricultural Research Institute at Pusa (Bihar). Maxwell
Lefroy became first Imperial Entomologist of Govt. of India.
1906 - “Indian Insect Pests” & “Indian Insect Life” Books by Professor Maxwell.
Subsequently State Governments also took up entomological work.
1914 - T.B. Fletcher, the first Government Entomologist of Madras State, published his
book "Some South Indian Insects".

8. 1916 –”Indian Forest of Economic Importance: Coleoptera; was published by the first
Imperial Forest Entomologist E.P. Stebbing”.
 1921 - Indian Central Cotton Committee to investigate on pests of cotton.
 1925 - Indian Lac Research Institute.
 1934- Hem Singh Pruthi as Imperial Entomologist, start ‘Entomological Society of India’ in
1938. Afzal Hussain was the first president of the society and VC were HS Pruthi and Ayyar.
 1940 - Dr. T.V. Ramakrishna Ayyar published the book "Handbook of Economic
Entomology" which met the long felt need of the students of Agriculture and agricultural
scientists as well and also known as “Father of Indian Entomology”.
 1968 - Dr. M.S. Mani's "General Entomology"
1969 - Dr. H.s. Pruthi's "Textbook of Agricultural Entomology". Dr. Pradhan's "Insect Pests
of Crops“
1946 - Government of India started the "Directorate of plant protection, quarentine and
storage.".
1960 - "The Desert Locust in India" monograph by Y.R. Rao.
1969 - "The monograph on Indian Thysanoptera" by Dr. T.N. Ananthakrishnan

9. o 1912– Plant Quarantine Act.
o 1914–Destructive Insects and Pests Act (DIPA).
o 1916–Imperial Forest Research Institute at Dehradun.
o 1925–Indian Lac Research Institute started at Ranchi.
o 1937–A laboratory for storage pests was started at Hapur, U.P.
o 1937- Establishment of Entomology division at IARI New Delhi.
o 1939–Locust Warning Organization established at Jodhpur.
o 1946–‘Directorate of Plant Protection, Quarantine & Storage at Faridabaad.
o 1968– ‘Central Insecticide Act’.
Institutes/Organizations

10. • NCIPM, New Delhi-(National Centre for Integrated Pest
Management - 1988).
• PDBC, Bangalore-(Project Directorate of Biological Control -1993).
• NBAIR-National Bureau of Agricultural Insect Resources and
formerly it is a NBAII, Bengalore in 1957.
• CIB, Faridabad – Central Insecticide Board.
• NPPTI, Hyderabad–National Plant Protection Training Institute.
Entomological Institutes

11. FACTORS FOR INSECTS ABUNDANCE
Measures of dominance
1. More number of species: In the animal kingdom more than 85 per cent of the
species belongs to insect group. Total number of insects described so far is more than
9 lakhs.
2. Large number of individuals in a single species: e.g., Locust swarm comprising of
109 number of individuals, occupying large area.
3. Great variety of habitats: Insects thrive well under varied conditions.
4. Long geological history: Insects were known to occupy this earth for more than
350 million years, which is a good track record. This has given the insects great
variety of adoptions under different conditions.

12. Reasons for dominance
1. Capacity for flight: Insects posess wings, which is the lateral extension of
exoskeleton. Insects are the earliest animals and the only flying invertebrates.
Flight is used for the following purpose-
i. To seek food, mate, shelter and oviposition sites
ii. To colonize in a new habitat and also to exchange habitat.
iii. To escape from enemies and unfavourable conditions.
iv. To migrate (i.e. for long distance travel e.g. Locusts)
2. Adaptability or Universality: Insects are the earliest groups to make their life
on the earth and to occupy vast habitats of soil and water.
i. Found in wide range of climatic conditions, from -50ñC to 40ñC.
ii. Psilopa petroli found in crude petroleum well.
iii. Ephydra fly living in great salt lake.
iv. Every flowering plant providing food for one or many Phytophagous insects.
v. Even the decomposing materials serving as food for many Saprophagous
insects.
vi. Many Carnivorous insects are parasitic on other animals and insects.

13. 3. Size: Majority of insects are small conferring the following physiological and
ecological advantages.
i. Less space, food, time and energy requirements for development and sustaining
life.
ii. Energy Utilization maximum.
iii. Less gravitational effect.
iv. Muscular action and tracheal respiration more effective.
v. Easy escape from enemies.
4. Exoskeleton: Insect body is covered with an outer cuticle called exoskeleton which
is made up of a cuticular protein called Chitin. This is light in weight and gives
strength, rigidity and flexibility to the insect body.
Uses:
i.Act as external armour
ii.Provides space for muscle attachment
iii.Prevents water loss

14. 5. Resistance to desiccation: Insects minimise the water loss from their body
surface through the following processes.
I. Prevention of water loss:
i. Lipids and polyphenols present in the Epicuticle acts as water proofing.
ii. Was layer with closely packed wax molecules prevents escape of water.
iii. Spiracles are closed to prevent water loss.
iv. In the egg stage shell development prevents water loss and desication of inner
embryos.
II. Conservation of water
i. Capable of utilizing metabolic water
ii. Rectal resorption of water from faeces.
iii. Terrestrial insects use less quantity of water to remove the nitrogenous waste
(Uric acid) which is water insoluble.
6. Tracheal system of respiration: This ensures direct transfer of adequate oxygen
to actively breathing tissues. Spiracles through their closing mechanism admit air
and restrict water loss.

15. 7. Reproductive potential: Reproductive potential of insect is high due to the
following reasons:
i Egg laying capacity (fecundity) is high. e.g., Queen termite lays 6000 - 7000 eggs per
day for 15 long years.
ii. Development period is short. e.g., Corn aphid produces 16 nymphs per female
which reaches the adulthood within 16 days. There by one generation is completed
within a short period of 16 days, which favours greater genetic changes in the insect
population, like quicker development of insecticide resistant strains.
iii. Careful selection of egg lying sites and protection of eggs.
iv. Exhibits parental care like progressive provisioning (e.g. bees) and mass
provisioning (e.g. Wasps)
v. Presence of special types of reproduction other than oviparity and viviparity.
* Polyembryony: Development of many individuals from a single egg. e.g. parasitic
wasps.
* Parthenogenesis: Reproduction without male or without fertilization, e.g. aphids
* Paedogenesis: Reproduction by immature stages. e.g. certain flies.

16. 8. Complete metamorphosis: More than 82 per cent of insects undergo complete
metamorphosis (Holometabolous insects) with the following four stages.
i. Egg: Inactive, inexpensive, inconspicuous and embryo develops inside.
ii. Larva: Active, feeds, digests, grows and store food.
iii. Pupa: Inactive, internal reorganisation and resist adverse conditions.
iv. Adult: Active, reproduce and disperse.
As the larval and adult food sources are different, competition for food is less.
9. Defense mechanisms: By using the following defense mechanisms, insects escape
from the enemies to increase their survival rate.
i. Behavioural: Thanatosis - insects pretends as if dead. e.g. some beetles.
ii. Structural e.g. hardened forewings of beetles known as elytra protect the beetles
from predation of birds.
iii. Colourational: Presence of protective colours. e.g.Stick insects
iv. Chemical: Presence of defensive chemicals. e.g. Bees producing venom
10. Hexapod locomotion: Insects uses 3 legs at a time during locomotion, while the
remaining 3 legs are static, which gives greater stability.

18. POSITION OF INSECTS IN ANIMAL KINGDOM

19. POSITION OF INSECTS IN ANIMAL KINGDOM AND ITS
RELATIONSHIP WITH OTHER ARTHROPODA
Classification: 7 classes.
Phylum : Arthropoda
Classes :
1. Onychophora (claw bearing)e.g. Peripatus, has similarities with arthropoda like
antenae, open circulatory system, walking legs with claw and tracheal system.
2. Crustacea (Crusta - shell)e.g. Prawn, crab, wood louse
3. Arachnida (Arachne - spider)e.g. Scorpion, spider, tick, mite
4. Chilopoda (Chilo - lip; poda - appendage)e.g. Centipedes (carnivorous)
5. Diplopoda (Diplo - two; poda- - appendage)e.g. Millipede (scavengers)
6. Trilobita (an extinct group)- The dominant arthropodes in the early Paleozoic
seas (many million ago)
7. Hexapoda or Insectae.g. Insects.

20. Characters of the Phylum Arthropoda: (Arthro-joint, poda-foot)
i. Segmented body
ii. Segments grouped into 2 or 3 regions known as Tagmosis
iii. Renewable chitinous exoskeleton
iv. Grow by moulting v. Bilateral symmetry
vi. Body cavity filled with blood-Haemocoel
vii. Tubular alimentary canal with mouth and anus
viii. Dorsal heart with ostia
ix. Dorsal brain with ventral nerve cord
x. Striated muscles
xi. No cilia
xii. Paired segmented appendages

23. • Insect body wall – Integument/Exoskeleton
• External covering – ectodermal in origin
• Rigid, flexible, lighter, stronger and variously
modified
Insect Integument: Structure and Function

24. • Consists of 3 layers :
Structure

25. • Outer non-cellular layer – has 2 sub-layers
• Epicuticle: outer most layer – very thin – devoid of
chitin
• Differentiated into 5 layers:
– Cement layer – outer most layer – made of lipid and tanned
protein – protects wax layer.
– Wax layer – contains closely packed wax molecules – prevents
desiccation
– Cuticulin – Non-chitinous polymerised lipoprotein layer –
barrier to ions
– Outer Epicuticle
– Inner Epicuticle (It contain wax filaments)
Cuticle....

26. • Procuticle – divided into 2 – Outer exocuticle & Inner
Endocuticle.
• Exocuticle: Outer layer – much thicker – composed of Chitin
& Sclerotin – Dark and rigid
• Endocuticle – Inner layer – thickest layer – made of chitin &
Arthropodin – Colourless, soft and flexible.
• Epidermis: Inner unicellular layer resting on basement
membrane – Functions:
– Cuticle secretion
– Digestion and absorption of old cuticle
– Wound repairing
– Gives surface look

28. Composition....
Chitin: Main constituent of cuticle
– Nitrogenous polysaccharide and polymer of N-
acetylglucosamine.
– (water insoluble and soluble in acids, alkalies and
organic solvents)
 Arthropodin: Untanned cuticular protein (water soluble).
 Sclerotin : Tanned cuticular protein (water insoluble).
 Resilin: Elastic cuticular protein – for flexibility of sclerites.

29. • Cuticular in growth of body wall – provide
space for muscle attachment. 2 types:
– Apodeme – hollow invagination of body wall
(ridge like)
– Apophysis – Solid invagination of body wall (spine
or fingure like)
Endoskeleton...

31. 31

32. • Clothing hairs, plumose hairs. e.g. Honey bee. Bristles. e.g. flies
32

33. • Scales - flattened out growth of body wall e.g. Moths and butterflies
33

34. • Glandular seta. et. caterpillar
34

35. • Sensory setae - associated with sensory neuron or neurons
35

36. • Seta - hair like out growth (Epidermal cell generating seta is known as
Trichogen, while
36

37. 37
• Multicellular
e.g.
Spur - movable structure
Spine- Immovable structure

38. • GLANDS
• Cuticular glands are either unicellular or multicellular.
• Following are some of the examples.
• i. Wax gland - e.g. Honey bee and mealy bug
• ii. Lac gland - e.g. Lac insects
• iii. Moulting gland secreting moulting fluid.
• iv. Androconia or scent scale - e.g.moth
• v. Poison gland - e.g. slug caterpillar
38

39. • Wax gland - e.g. Honey bee and mealy bug
39

40. • . Lac gland - e.g. Lac insects
40

41. • Moulting gland secreting moulting fluid
41

42. • Poison gland - e.g. slug caterpillar
42

43. Functions of Body wall
i. Acts as external armour and strengthen external organs like jaws and ovipositor
ii. Protects the organs against physical aberation, injurious chemicals, parasites,
predators and pathogen.
iii. Internally protects the vital organs, foregut, hindgut and trachea.
iv. Provides space for muscle attachment and gives shape to the body.
v. Prevents water loss from the body.
vi. Cuticular sensory organs helps in sensing the environment.
vii. Cuticular pigments give colour.
43

44. MOULTING (Ecdysis)
• Ecdysis
• Periodical process of shedding the old cuticle accompanied by the formation of
new cuticle is known as moulting or ecdysis.
• The cuticular parts discarded during moulting is known as Exuvia.
• Moulting occurs many times in an insect during the immatured stages before
attaining the adult-hood.
• The time interval between the two subsequent moulting is called as Stadium and
the form assumed by the insect in any stadium is called as Instar.
44

45. • Steps in moulting
1. Behaviroual changes: Larva stops feeding and become inactive.
2. Changes in epidermis: In the epidermis cell size, its activity, protein content and
enzyme level increases. Cells divide miotically and increases the tension, which
results in loosening of cells of cuticle.
45

46. 3. Apolysis: Detachment of cuticle from epidermis
4. Formation of Sub cuticular space
5. Secretion of moulting gel in the sub cuticular space which is rich with chitinase and
protease.
6. New epicuticle formation: Lipoprotein layer (cuticulin) is laid over the epidermis.
46

47. 7. Procuticle formation: Procuticle is formed below the epicuticle.
8. Activation of moulting gel: Moulting gel is converted into moulting fluid rich in
enzymes. This activates endocuticle digestion and absorption.
9. Wax layer formation: Wax threads of pore canals secrete wax layer.
10.Cement layer formation : Dermal glands secretes cement layer (Tectocuticle).
47

48. 11.Moulting: This involves two steps
i. Rupturing of old cuticle: Insect increases its body volume through intake of air or
water which enhances the blood flow to head and thorax. There by the old cuticle
ruptures along predetermined line of weakness known as ecdysial line
ii. Removal of old cuticle: Peristaltic movement of body and lubricant action of
moulting fluid helps in the removal of old cuticle. During each moulting the
cuticular coverings discarded are the cuticular of legs, internal linings of foregut and
hindgut and trachea.
12.Formation of exocuticle: The upper layer of procuticle develops as
exocuticle through addition of protein and tanning by phenolic substance.
13.Formation of endocuticle: The lower layer of procuticle develops as
endocuticle through addition of chitin and protein. This layer increases in
thickness.
48

49. • Control of Moulting: It is controlled by endocrine gland like prothoracic gland
which secrete moulting hormone. Endocrine glands are activated by prothoracico-
tropic hormones produced by neurosecretory cells of brain.
49

50. • Moulting: Shedding of old cuticle accompanied by formation of new cuticle is
called Moulting or Ecdysis.
• Detachment of cuticle from the epidermis is apolysis
• The time interval between two moults is called a stadium
• The formation of an insect during a stadium is called an instar
• The cast off skin by an insect is called as exuviae
• Chitin which makes up the exo-and endocuticle is a nitrogenous polysaccharide
formed from long chains N-acetyl D-glucosamine units (C8H13O5N)n
50

51. BODY SEGMENTATION OF
INSECT & INSECT HEAD

52.  Cockroach and Grasshopper is a typical insect as it
possesses all important characters of class insect.
 In general, insect body is divided in to a series of
rings or segments are known as “somites” or
“metameres”.
 The type of arrangement of these body segments in
embryonic stage is known as primary segmentation
while in adult insects is known as the secondary
segmentation.

53.  Insect body is divided in to three regions or tagmata
namely head, thorax and abdomen.
 This grouping of body segments in to regions is known as
tagmosis.
 Head consists of 6 segments i.e., 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 possess one pair of wings.
 Abdomen has 11 segments with genital appendages on
8th and 9th segments.
 The insect body generally consists of 20 segments.

54. Fig. General Organization of Insect Body

55. INSECT HEAD

56.  It is the foremost part in insect body consisting of 6 segments that
are fused to form a head capsule. Labral, antennary, ocular,
mandibular, maxillary and labial segments.
 The head segments can be divided in to two regions i.e.
procephalon and gnathocephalon (mouth).
 Head is attached or articulated to the thorax through neck or cervix.
 Head capsule is sclerotized and the head capsule excluding
appendages formed by the fusion of several sclerites is known as
cranium.
 Inside the head, an endoskeletal structure called the tentorium
which give supports to the brain, and provides a rigid origin for
muscles of the mandibles and other mouthparts.
 Head is concerned with feeding and sensory perception.

57. Types of head position
 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 and 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 kwown
as Orthopteroid type. Eg: Grass hopper, Cockroach.

58. (b) Prognathous : (Pro– infront and 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

59. (c) Opisthognathous : (Opistho– behind and
Gnathous Jaw)
 It is same as prognathous but mouthparts are directed
backward and held in between the fore legs. This is
also kwown as Hemipteroid or Opisthorhynchous type.
Eg: bugs, Mosquito

60. SCLERITES AND SUTURES OF HEAD
 The head capsule is formed by the union of number of
sclerites or cuticular plates or areas which are joined
together by means of cuticular lines or ridges known as
sutures or any of the large or small sclerotized/harden
areas of the body wall.
 These sutures provide mechanical support to the
cranial wall.
Suture
 The sclerites separated from each other by means of
thin impressed line called suture. (Sometimes referred
as a sulcus).

61. Generally insect possess the following sclerites:
1. Vertex: It is the top portion of epicranium which lies behind the
frons or the area between the two compound eyes.
2. Clypeus: It is situated above the labrum, separated by fronto-clypeal
suture & also separated from gena by clypogenal suture.
3. Frons: It is unpaired, facial part of the head capsule lying between the
arms of epicranial suture. Facial area below the vertex and above
clypeus
4. Gena: It is the area extending from below the compound eyes to just
above the mandibles. It is separated from frons by frontoganal suture
and from clypeus clypogenal suture.

62. 5. Occiput : Cranial area between occipital and post
occipital suture.
6. Post occiput: It is the extreme posterior part of the
insect head that remains before the neck region.
7. Occular sclerites: These are cuticular ring like
structures present around each compound eye.
8. Antennal sclerites: These form the basis for the
antennae and present around the scape.

63. Fig. Anterior view or face view

64. The common sutures present in head are:
1. Clypeolabral suture: It is the suture present
between clypeus and labrum.
2. Clypeofrontal suture or epistomal suture: The
suture present between clypeus and frons.
3. Epicranial suture: It is an inverted ‘Y’ shaped suture
distributed above the facial region extending up to
the epicranial part of the head.
4. Occipital suture: It is ‘U’ shaped or horseshoe
shaped suture between epicranium and occiput.

65. 5. Genal suture: It is the sutures present on the lateral
side of the head i.e. gena.
6. Post occipital suture: It is the only real suture in
insect head. Posterior end of the head is marked by
the post occipital suture to which the sclerites are
attached. As this suture separates the head from the
neck, hence named as real suture.
7. Occular suture: It is circular suture present around
each compound eye.
8. Antennal suture: It is a marginal depressed ring
around the antennal socket.

67. Insect Thorax
And abdomen

68. Thorax
• Middle tagma
• Three segmented - pro, meso and meta
• Meso and meta thorax with wing are called as Pterothorax
• Thorax is made of three scleritic plates
1. dorsal body plate - Tergum or Nota
2. ventral body plate (Sterna)
3. lateral plate (Pleura)

69. Thoracic nota
• 3 segments - pronotum, mesonotum & metanotum
respectively
• Pronotum - undivided & Saddle shaped in grass hopper,
Shield like in cockroach
• Pterothoracic notum - have 3 transverse sutures (Antecostal,
Pre scutal and Scuto-scutellar)
&5 tergites(Acrotergite, Prescutum, Scutum, Scutellum and
Post-scutellum)

70. Thoracic sterna
• Vental body plate - prosternum,
mesosternum and metasternum
• Made up of a segmental plate called
Eusternum and a intersternite called Spinasternum
• Eusternum - made of three sclerites -
presternum, basisternum and sternellum

71. Thoracic pleura
• Lateral body wall between notum & sternum
• Selerites of pleuron is called as pleurites
• fuse to form Pleural plate
• Pleural plate is divided into anterior episternum
and posterior epimeron by Pleural suture
• Pterothoracic pleuron provides space for
articulation of wing and
• Two pairs of spiracles are also present in the
mesopleuron and metapleuron.

72. ABDOMEN
• Third and posterior tagma
• This tagma is made up of 9-11 Uromeres
(segments) and is highly flexible
• abdominal segments are interconnected by a
membrane called conjunctiva
• Each abdominal segment is made up of only
two sclerite
1. Tergum 2. Sternum

73. ABDOMEN
• Eight pairs of spiracles in - first eight abdominal
segments
• in addition to a pair of tympanum in the first
abdominal segment
• Eight and ninth segments - female genital structure
• Ninth segment - male genital structure.
• Cerci

74. INSECT ANTENNAE:
STRUCTURE,
FUNCTIONS AND
MODIFICATIONS

75. 75
What is Antenna (Plural= Antennae)?
“Antennae are paired, freely mobile, segmented sensory
appendages articulated with the head in front of or between
the eyes. Antennae are also known as feelers.”
These are well developed in adults and poorly developed in
immature stages. Antennae are absent in order Protura and
Class Arachnida while 2 pairs of antennae present in Class
Crustacea.

76. 76
Structure of Antenna
“Antennae are multi segmented and may be divided into 3 parts:-
1. Scape:- It is the basal segment of a antenna, by which it is
attached with the head.
2. Pedicel:- It is the second segment of antenna which is shorter
than scape. This segment having a sensory apparatus named
‘Johnston organ’.
3. Flagellum:- It is the last segment of antenna which consists
the remaining divisions of antenna and it greatly varies in its
form and structure. It is also known as Clavola.

77. 77
Structure of Antenna

78. 78
Functions of Antennae
The main function of antenna is
sensory, which is modified
according to habit and habitat of
insect as given below:-
1. Organs of smell:- Some insects
have smell organs on their
antennae by which they
recognise their food. E.g. Ant,
Honey Bee and Jiant moths.

79. 79
2. Organs of taste:- Some insects
have taste hairs on their
antennae by which they
recognise the taste of their
food. E.g. Cockroach.

80. 80
4. Chordotonal Organs:- Hearing organs
(Jhonston’s organ) found in second
segment (pedicel) of antenna. e.g.
Male mosquito, Green bottle fly and
Paper wasp etc.
5. Sexual Dimorphism:- Some insect
belonging to the order Diptera and
Hemiptera, having different type of
Antenna in male and female, which
help in sexual dimorphism. e.g. Male
and Female Mosquito.

81. 81
7. Other Functions:-
(a). Help the mandibles
for holding the prey.
(b). Useful for clasping the
female during copulation.
(c). Butterfly bears some
transmitting and receiving
organs in their antennae.

82. 82
Modifications of Antennae
On the basis of shape and structure,
the antennae may be following type:-
1. Setaceous:- These are bristle like
antennae, in which segments
gradually decrease in size from
base to apex and tappering into a
point, presenting a whip like
structure.
e.g. Cockroach and Cricket.

83. 83
2. Filiform (Thread like):- It is
thread like antenna in which
segments are uniform in
thickness throughout from
base to apex and never ends
with bristle.
e.g. Insect of order
Orthroptera, Coleoptera
namely Grasshopper and
Ground Beetle.

84. 84
3. Moniliform (Like string of
beads):- Such type of
antennae have globular or oval
shaped segments with uniform
thickness from base to apex,
by which it looks like string of
beads. It have constriction
between the joints.
e.g. Insect of order Isoptera
namely Termite.

85. 85
4. Pectinate (Comb like):- This is a
comb like in structure in which
each segment of the antenna
possess long projection on one
side, giving comb like
appearance.
e.g. Insect of order Lepidoptera
namely Moth of Sugarcane root
borer.

86. 86
5. Bipectinate (Double Comb
like):-In this type of
antenna, each segment has
the long projections on
both side, giving double
comb like appearance.
e.g. Insect of order
Lepidoptera namely Silk
Moth.

87. 87
6. Serrate (Saw like):-In this type
of antenna, each segment is
more or less triangular and
projected on one side, which
giving teeth of saw like
appearance.
e.g. Insect of order Coleoptera
namely Pulse beetle.

88. 88
7. Flabellate (Feather like):- In
this type of antenna, in which
projections of the flagellum
become long and form a
feather like structure, which is
known as flabella.
e.g. Insect of order Coleoptera
namely Cedar Beetle.

89. 89
8. Plumose (bursh like with
dense hairs):- In this type of
antenna, each segment has
the whorls of hairs arise from
their joints and look like
plumose.
e.g. Insect of order Diptera
namely Male Mosquito.

90. 90
9. Pilose (bursh like with sparse
hairs):- In this type of antenna,
each segment has the whorls
of hairs arise from their joints
like plumose but whorl
contains less number of hairs.
e.g. Insect of order Diptera
namely Female Mosquito.

91. 91
10. Whorled:- Basically these are
the setaceous, filiform or
moniliform type of antennae
in which each segment has a
whorl of bristle at every
joint.
e.g. Insect of order
Hemiptera namely Male of
Mango Mealy Bug.

92. 92
11. Clavate (Clubbed):- In this type
of antenna, segments gradually
increase in diameter towards
the tip and last segment finally
ending into a round core, look
like club.
e.g. Insect of order Lepidoptera
namely Butterfly.

93. 93
12. Capitate (Clubbed with Knob):-
In this type of antenna,
segments gradually increase in
diameter towards the tip and
suddenly last 3-5 segments
enlarge to form a knob like
structure.
e.g. Red Rust Flour Beetle.

94. 94
13. Lamellate (Plate like):- This
is a modification of capitate
antennae in which terminal
segments extended on the
side to form leaf like plate
instead of forming the knob.
e.g. Rhinoceros Beetle, Dung
Rollers etc.

95. 95
14. Geniculate (Elbowed):- In this
type of antenna, the scape is
greatly elongated, pedicel is
short and flagellum is made
up of small segments which
make a bent on the scape look
like knee.
e.g. Ants, Honey Bee etc.

96. 96
15. Aristate (With arista):- In this
type of antenna, scape is
smaller and broader, pedicel
is longer than scape. The
flagellum is longer than both
and bears heavy bristle
known as arista.
e.g. House Fly.

97. 97
16. Stylate (With style):- In
this type of antenna, last
segment of flagellum is
modified into a long
bristle known as style.
e.g. Snipe fly, Robber fly.

98. 98
17. Fusiform:- In this type of
antenna, scape is smaller
and thin, while pedicle is
larger and flagellum is
modified into a hook like
structure.
e.g. Sphingid Moth.

99. DIFFERENT TYPES OF MOUTHPARTS
Biting and Chewing type
Chewing and lapping type
Lacerating and sucking type
Piercing and sucking type
Sponging type
Siphoning type
Mask type
Degenerate type

100. BITING AND CHEWING MOUTH
PARTS
 ORDER: ORTHOPTERA, eg: grasshopper
Mouth parts are typical mandibulate type useful
for biting, chewing and consisting of
 Labrum (upper lip)
 Mandibles (Ist pair of jaws)
 Maxillae (first maxilla-2nd pair of jaws)
 Labium (second maxilla or lower lip-3rd pair of
jaws)
 Hypopharynx (tongue).

102. Labrum:
 A simple plate like structure situated below
the clypeus on the anterior side of the head
and moves up and down.
 The functions of the labrum are to close the
front of the moth cavity, protect the
mandibles, guide the food into the mouth.

103. Mandibles:
 Paired un segmented, heavily sclerotized
jaws lying immediately below the labrum.
 Articulate with the headcapsule side wise by
means of two joints; ginglymus and condyl.
 Possess two types of teeth; incisors and
molars.
 Adopted for cutting and masticating the food
material.

104. Maxillae:
 Paired segmented structures lying below the
mandibles.
 Each maxilla bears a feeler-like organ, the palpus
(which discharges a gustatory or tasting function).
 Have two segments, the basal cardo and apical
stipes.
 Palpus arise on a lobe of the stipes called the
palpifer.
 Stipes bears two lobe like structures at its apex
(outer simple galea and inner jaw like structure
lacinia)
 Functionally maxillae are of accessory jaws, their
lacinia aiding mandibles in holding the food.

105. Hypopharynx:
 A short tongue like structure located above
the labium and between the maxillae.
 The ducts from salivary glands open on or
near the base of hypopharynx.
Labium:
 Lies behind the maxillae
 Derived by the fusion of the second pair of
maxillae, hence also referred as the second
maxillae.

106.  Divided by transverse suture (labial suture)
into two portions, basal postmentum and distal
prementum
 Postmentum is usually divided into basal
submentum and distal mentum.
 Prementum bears a pair of palpi called labial
palpi and a group of apical lobes which
constitute the ligula.
 Labial palpi arise on lateral lobes of the
prementum called palpigers.
 Ligula consists of a pair of small lobes in the
middle, inner glossae and outer paraglossae.
 Labial palpi act as sense organs comparable
to the gustatory function of maxillary palpi.

107. Biting and chewing mouth parts

108. Biting and chewing mouthparts

109. Feeding mechanism :
 The labrum or upper lip helps the insect to pull the
food into the mouth.
 Mandibles masticate the food. They cut off the food
material. Small teeth present in each mandible work
against those of the opposite for effective grinding.
 The maxillae aid in holding the food in mouth while it
chewed by mandibles. They also aid in breaking up
the food.
 Both maxillae and mandibles move side ways.
 Labial palpi works similar to that of maxillary palpi.
 The maxillae and labium helps in passing the food
into oesophagus

110. Grasping Type
 Mandibles – slender, elongate, curved at their
ends bearing 1-3 sharp teeth. Extreme
development in males of many of the Lucanidae
and Chiasognathus
 Maxillae – Single-lobed in lucanids called “mala”
 Other parts – normal
 Soldiers of Termites – Large, twisted,
asymmetrical mandibles with peculiar “snapping
action”. Some posses salivary or frontal glands
(adhesive secretions).
 Examples : Soldier termites and stag beetles
(Lucanids)

111. Grasping
Type
Soldier termite

112. GRASPING AND SUCKING TYPE
 Mandibles and maxillae – long, exerted
adopted for seizing the prey
 Mandibles – sickle – shaped and armed with
teeth. Grooved along their ventral surface and a
lobe or maxillae (perhaps lacinia) similar in size
and shape fits each groove forming a pair of
imperfect suctorial tubes. Blood imbibed by
means of pumping action of pharynx.
 Maxillary palpi – absent; labium – greatly
reduced,
 labial palps - variable or aborted
 Examples: larvae of Antlions and Aphid lions,
Lampyrid larvae.

113. GRASPING AND SUCKING
TYPE
Antlion larva

114. . SCRAPING TYPE
 Mouthparts – adopted for dealing with liquid
and soft food.
 Labrum – membranous and concealed
 Mandibles – membranous, thin, sometimes
concealed, incapable of biting, used for
moulding wax mud, dung etc.
 Maxillae – inverted with long hairs, used for
feeding pollen (in pollen feeders)
 Ligula sometimes atrophied, galeae – free
 Examples : Pollen feeders (e.g. Yucca moth,
Tegeticula yuccasella feeding on Yucca
filamentosa) dung beetles (Scarabaeinae)

115. Dung beetle

116. BITING AND MASTICATION AND LICKING TYPE
 Mandibles – eventually biting nature
 Maxillae – Comparatively little modified, palps are 6-
segmented
 Laciniae – reduced to small scales
 Galeae – broad membranous lobes
 Labium – large shield – shaped prementum; bearing
4-segmented labial palps
 Ligula – curiously elongated paraglossae and a wide
bilobed glossa.
 Examples : Vespula germanica (worker) and the
Primitive bee (Hylaeus)

117. BITING AND MASTICATION AND LICKING TYPE
Vespula germanica

118. SIPHONING OR SIMPLE SUCKING
TYPE
 Order: Lepidoptera, e.g.: butterflies and moths
 Mandibles totally absent. Majority of Lepidoptera
mandibles are wanting and maxillae to form a
suctorial proboscis
 Maxillae is composed of elongated galea. Each galea
of maxillia elongated, semi-circular towards inner
side. Galea of both the sides meet together forming
into a tubular structure, proboscis.
 Observe the coiled proboscis beneath the head.
 Liquid food is imbibed through groove formed by
galea

119.  All other mouth parts highly reduced.
 When fully developed mouth parts, maxillary palpi are
5 or 6 segmented.
 Labium reduced to small ventral plate.
 Hypopharynx is present on floor of mouth.
Feeding mechanism:
 When not in use, proboscis is spirally coiled and
beneath the thorax.
 It presents an extraordinary variation in length. Eg.
Sphingidae, Danaus.
 According to Breitenback they are often developed
into denticulate spines.
 Proboscis extended by blood pressure. Eastham and
Eassa (1955).

121. SIPHONING
OR SIMPLE
SUCKING
TYPE

122. PIERCING AND SUCKING TYPE
 Order : Hemiptera
 Mandibles and maxillae being modified to form
slender bristle like stylet which rest in grooved
labium.
 Both pairs of stylets are hollow seta-like structures.
 These stylets back into prothorax (Cranston and
Sprague, 1961).
 Stylets withdrawn into a pocket connected with the
channel of the labium.
 Mandibular stylets form anterior (outer) pair and
posterior pair of stylets (inner) constitute part of
maxilla.
 Dorsal stylet as a suction canal.

123.  Ventral stylet as a salivary canal.
 Labium no part in perforating the tissue of host plant.
 Hypopharynx is highly specialized in Hemiptera.
 Salivarium is modified into a powerful salivary pump.
Feeding mechanism:
 At rest rostrum is flexed beneath the body.
 In most Hemiptera stylets are only slightly longer than
the rostrum. Eg. Aphididae, Lygus.
 In Coccoidea stylets are forced deeper and deeper
into the plant.
 Mandibles are first pushed then followed by maxillae.

124. PIERCING
AND
SUCKING
TYPE

126. SPONGING TYPE
 Eg: HOUSEFLY.
 Mandibles are absent.
 Maxillae are represented by a pair of maxillary palp.
 Labium is divided into basal rostrum, middle
haustellum and distal labellar lobes. Labella are
tranversed by small channels known as pseudotrachia
which converge at one point and open into the food
channel.
 Epipharynx and hypopharynx together form the food
channel which leads to Oesophagous

129.  Mode of feeding: It is used for food which is
either liquid or readily soluble in saliva. While
feeding after dissolving the food by saliva, the
labella is thrust into the liquid food as a result
the pseudotracheae get filled with the liquid
by capillary action. The food is then passed
through the food channel to the
Oesophagous Eg. Houseflies

130. CHEWING AND LAPPING TYPE
Eg: HONEYBEES
 Mandibles and labrum are of chewing type and help
in bolding the food.
 Maxillae and labrum are elongated and united.
There are suspended from the cranium and
articulate to it through the base of the maxillae.
Maxillae :
 Palps are very small
 Galea with its concaves inner surface forms a roof
over the glossa and fits length wise against labial
palps. In this way a food channel is formed.

131. Labium:
Palps are long and form food channel with
galea
Glossae are fused to form a channeled
organ termed as alaglossa which can
reach deep into nectar of blossoms.
Mode of feeding: The mandibles and
labrum help in holding food / prey. In
honey bees the labrum is used for molding
wax into cells. Regarding intake of nectar
king, Imm’s and Snodgrass gave their own
view.

132. King’s Views: After sucking the nectar with
the tip of glossa, it is retracted into labial palp
and galea, where the latter squeezes off the
nectar which is deposited at the base of the
glossa in a small cavity formed by the
paraglossa. Finally as a result of bending of
the labium upward, the base of the glossa
comes near the mouth cavity and the
accumulated nectar is sucked into the
Oesophagous by the action of the pharyngeal
pump.

133. CHEWING AND LAPPING TYPE

134. MASK TYPE
 These are modified biting and chewing type.
 Labrum, mandibles, maxillae, hypopharynx are typically
developed as in biting type of mouth parts.
 Labium – in the nymph this organ is modified for prehensile
purpose and is known as mask.
 The prementum and post mentum are markedly lengthened.
 The ligula is undivided and represented by a median lobe which
is fused with the prementum.
 The labial palpi are modified to form a lateral lobes each of
which carries on its outer side a movable hook.
 These hooks which help in catching the prey.
 Ex : Dragon fly naiads.

135. Naiad

136. DEGENERATE TYPE
 Eg: MAGGOTS
 In maggots, a definite head is always absent.
 The mouth parts are highly reduced and are
represented y one or two mouth spines or
hooks.
 Hypopharynx, clypeus and associated sclerites
of the head form upper pharyngeal skeleton or
hypopharyngeal sclerite around the beginning
of the alimentary canal.

137. DEGENERAE TYPE

138. Lacerating and sucking or rasping
and sucking type
• Order: Thysanoptera. eg. Thrips.
• Labrum, labium and bases of maxillae
combine and unite to form a mouth
cone.
• Both maxillae and the left mandible are
modified as stylets.
• Right mandible rudimentary.
• Hypopharynx reduced.

139. Thrips

140. 140
Insect Legs and their
modifications
“An insect usually bears three
pairs of legs which are located on
the ventral surface of thoracic
segments. They are primary
organs for running or walking, but
according to the habit and habitat
of insects they are modified for
different purposes.”

141. 141
Structure of Insect Leg
A typical leg consists of the following parts:-
a) Coxa:- It is the basal segment and joint the leg with thorax.
b) Trochanter:- It is the small second division of the leg which
articulates with coxa but is usually fixed with femur.
c) Femur:- It is the largest and most powerful division of the leg.
d) Tibia:- It is the slender, usually quite long.
e) Tarsus:- It is the fifth divisional segment and generally sub
divided into 2-5 segments.
f) Pretarsus:- It is the last terminal segment of the leg which
represented of the leg which is represented by a complex set
of claws.

142. 142

143. 143
Modifications of
Leg
1. Ambutorial or Walking Type:-
It is generalized form of insect
leg, which is usually adapted
for walking.
Example:- Cockroach and Bugs

144. 144
2. Cursorial or Running Type:- It is
almost similar to walking type
of leg, but it is differentiated by
the tarsus which is
comparatively longer and
touches the ground while
running.
Example:- Ants, Blister Beetle
and wasps.

145. 145
3. Saltatorial or Jumping Type:-
Such type of legs are present
in grasshopper, crickets and
flea beetle where the femur
of the hind leg get enlarged
and accomodates the
powerful tibial muscles.
Example:- Hind leg of
Grasshopper

146. 146
4. Scansorial or Clinging Type:-
This type of legs are smaller
and flat. The coxa are widely
separated and tarsi bears a
single claw.
Example:- Head Louse

147. 147
5. Fossorial or Digging Type:- This
type of legs are modified for
the purpose of digging. These
are powerful, broad and small
in size. Tibia and tarsus short
and broad with teeth like
projections.
Example:- Mole crickets and
Dung rollers.

148. 148
6. Raptorial or Grasping Type:-
Such legs are adapted for
catching the prey and are
found in Mantids. Coxa of fore
leg is more elongated whereas
the trochanter is small. Tibia is
spinous and fits along the
femur.
Example:- Preying Mantids

149. 149
7. Natatorial or Swimming Type:-
These type legs are found in
insects which lives in the water
and help them to swim. The
femur, tibia and tarsus are
flattened and posses the long
rows of hairs.
Example:- Dytiscus and Jaint
water bug.

150. 150
8. Foragial or Pollen Collecting
Type:- This type of legs are
found in worker honey bees
which is mainly adapted for
carrying the pollen from the
flowers. Tibia of the hind leg is
dialated and covered with longs
dense hairs which forms a
pollen basket.
Example:- Hind leg of Woker
Honey Bee.

151. 151
9. Stridulatorial or Sound
Producing Type:- These legs
are typically adapted for
producing sound wherein the
femur of hind leg is provided
with the row of pegs on its
inner side. These femoral pegs
work against the outer surface
of each tergum or coastal
margin of the fore wing,
thereby producing a sound.
Example:- Male Grasshopper
and cricket.

152. 152
10. Sticking Type:- In such type of
legs the pretarsus is highly
modified in a pair of claws and
a pair of pad like structure
known as pulvilli (found at the
base of claws). Hollow and
tubular hairs secrets a sticky
substance. These are also
known as Adhesive type of
legs.
Example:- House fly.

153. 153
11. Clasping Type:- This Such type
of legs are modified for
reproduction purposes. Coxa
and Trochater is comparatively
smaller while the Femur is
thick. The tibia is slender, tarsus
is one segmented and arched.
This adaptation helps male to
holds the female during
reproduction.
Example:- Chleredryinus
(Parasite of Sugarcane Pyrilla)

154. 154
12. Suctorial or Sucking Type:- This
type of legs are also modified
for the purpose of
reproduction in which coxa and
trochanter of fore legs are
small while femur is thick and
small. They are also helpful in
sticking with grasses and leaves
against the water flow.
Example:- Male Dytiscus.

155. 155
13. Antennal Cleaning Legs:-
This type of legs are
modified for the purpose of
cleaning antennae in which
tibia possess a movable
spine and the first tarsal
segment with a semi-circular
notch.
Example:- Front legs of
Honey Bees.

156. 156
14. Wax Pick Legs:- This type of
legs are modified for the
purpose of picking of wax
plate in which Tibia possess a
spine called wax pick for
removing the wax plates
from the ventral side of the
abdomen.
Example:- Middle legs of
Honey Bees.

157. 157
15. Prehensile:-
This type
of legs are modified
for the purpose of
catching prey and
basket forming.
Example:- Dragon
Flies.