Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae. Insects are the most diverse group of animals; they include more than a million described species and represent more than half of all known living organisms. Nearly all insects hatch from eggs. Insect growth is constrained by the inelastic exoskeleton and development involves a series of molts. The immature stages often differ from the adults in structure, habit and habitat, and can include a passive pupal stage in those groups that undergo four-stage metamorphosis. Insects that undergo three-stage metamorphosis lack a pupal stage and adults develop through a series of nymphal stages.[6] The higher level relationship of the insects is unclear. Fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonflies with wingspans of 55 to 70 cm (22 to 28 in). The most diverse insect groups appear to have coevolved with flowering plants. Adult insects typically move about by walking, flying, or sometimes swimming. As it allows for rapid yet stable movement, many insects adopt a tripedal gait in which they walk with their legs touching the ground in alternating triangles, composed of the front and rear on one side with the middle on the other side. Insects are the only invertebrates to have evolved flight, and all flying insects derive from one common ancestor. Many insects spend at least part of their lives under water, with larval adaptations that include gills, and some adult insects are aquatic and have adaptations for swimming. Some species, such as water striders, are capable of walking on the surface of water. Insects are mostly solitary, but some, such as certain bees, ants and termites, are social and live in large, well-organized colonies. Some insects, such as earwigs, show maternal care, guarding their eggs and young. Insects can communicate with each other in a variety of ways. Male moths can sense the pheromones of female moths over great distances. Other species communicate with sounds: crickets stridulate, or rub their wings together, to attract a mate and repel other males. Lampyrid beetles communicate with light.

2. INSECTS
Insects or Insecta (from Latin insectum) are hexapod
invertebrates and the largest group within the arthropod
phylum.
Insects have a chitinous exoskeleton, segmented bodies, and
jointed legs.

3. INSECTS
Insects are distinguished from other arthropods by their
body, which is divided into three major regions :
1) THE HEAD, which bears the mouthparts, eyes, and a pair
of antennae,
2) The three segmented THORAX, which usually has three
pairs of legs (hence “Hexapoda”) in adults and usually one
or two pairs of wings, and
3) The many segmented ABDOMEN, which contains
digestive, excretory, and reproductive organs.

4. Why Insects ?
Insects do matter too...

6. Why Insects are the most successful
group of animals on the earth ?
* Ancient
* Numerous
* Habitat
* Parental care
* Food
* Protection
* Tolerance
* Flight
* Fecundity
* Exoskeleton
* Size
* Reproductive potential
* Metamorphosis
* Economical & Ecological
importance
* Culture & religion
* Language
* Medical science & technology

7. ANCIENT
Insect fossils are found in geological era
which is about 250 million years old.
Insects are not only older than man
but they have survived
and flourished during these periods
which are certainly proof of their success.
Their study is the field of
paleoentomology.
The age of giant insect

8. NUMEROUS
They are 6 times more than all animal
species and 10 times more than
vertebrates.
Their total population is 10 which
works out to be 3 lakh insects per
human being.
Only 1 million insects are known to
science.

9. HABITAT
They are abound in all known habitats
(except sea) ,
such as air, water, soil, desert,
hot springs, in animals and plants
and even such inhospitable environments
as
petroleum (a dipteran larva),
potassium bitartrate (some beetles).
No animals can claim such a versatility.
Soil habitat
Water habitat
Air habitat

10. PARENTAL CARE
Parental care is an indication of higher
evolution.
Parental care is developed particularly
in social insects -
ants, bees, wasps and
termites which take good care of their
brood.

11. FOOD
There is no organic material that the
insect do not eat.
Those insects that feed on plants eat
everything that form their part even they
would feed on
green plants, dry plants, decayed plants
and paper.
Those insects that feed on animals would
eat anything of the animal even they feed
upon other insects or their secretion and
excretion.
( Honeydew of aphids eaten by ants and
wax moth feed upon wax.)
Leaf feeder
Animal feeder
Paper feeder

12. PROTECTION
No other animal group posses as that
many protective device as insects does
like
exoskeleton, stinging hair, apparatus
which are poisonous and repugnatory
glands (defensive gland) as
mimicry, camouflage, and habitual
activities like stillness to feign death to
escape from enemy attention.
Exoskeleton
Camouflage
Camouflage

13. TOLERANCE
Inspite of being cold blooded animals,
insects can tolerate temperature as high
as 48-52℃
(some dipterans and Coleopterans
found in hot springs of Western united
states)
And as low as 20-30℃
(Promethean moth and some
Coleopterans).
Cockroaches can also tolerate to a very
high temperature.
Promethean moth

14. FLIGHT
Insects are the only invertebrates that
can fly. Their advantages are -
They can migrate from one
unfavourable condition to a more
favourable condition.
Can go in search of food to long
distances.
Can reach their mates at a distance
quickly.
Can hope to be more safer in air.

15. FECUNDITY
They are prolific breeders.
They produce 100-150 eggs per female on
an average.
They are some like honeybee queen that
produce 2-3 thousand eggs per day and
termite queen 60 eggs per sec.
But survival rate of insect is very low (2
per 2000 larvae in case of housefly).
They adopt all methods of reproduction.
Honeybee eggs
Termite eggs
Housefly eggs

16. EXOSKELETON
Exoskeleton is an outer covering of
body.
It is made up of chitin.
It provides.,
Protection to underlying delicate
organs.
Checks evaporation and conservative
of water which is important to every
terrestrial animals.
Insects can camouflage for their
defense.

17. SIZE
The insects size can be put at two
extremes,
Brazilian moth i.e. 280 mm wing span and
the smallest American beetle i.e. 0.2 mm
long,
but their average size is small which give
many important advantages like.,
They require less food.
They require less space
Their shorter muscles can lift higher
weight,
Being small insects have a greater chance
of escaping from their larger sized
enemies.
Ascalapha odorata
scydosella musawasensis

18. Reproductive success is one of the
most significant measures of an
organism's fitness.
In insect populations,
females often produce large numbers
of eggs (high fecundity),
most of the eggs hatch (high fertility)
and,
the life cycle is relatively short (often
as little as 2-4 weeks).
Together, these three characteristics
enable insects to produce remarkably
large numbers of offspring.
REPRODUCTIVE
POTENTIAL

19. Most insects undergo significant
developmental changes as they grow
from immatures to adults.
These changes,
collectively known as metamorphosis,
may involve physical,
biochemical, and/or behavioral
alterations that promote survival,
dispersal, and reproduction of the
species.
In the more primitive insects,
most of these changes occur gradually as
the animal matures.
METAMORPHOSIS

20. Insets are crucial components of many
ecosystems, where they perform
many important functions.
They aerate the soil, pollinate
blossoms, and control insect and plant
pest.
Many insects, especially beetles, are
scavengers, feeding on dead animals
and fallen trees, thereby recycling
nutrients back into the soil.
ECOLOGICAL & ECONOMICAL
IMPORTANCE
Scavengers

21. In view of their abundance and the range
of their impact on the lives of our early
ancestors,
It is not surprising that insects have
become thoroughly integrated into
human culture from arts and crafts to
mythology and religion.
The religious and symbolic significance of
these insects was often reflected in the
art, literature, music,
and dance of the times.
RELIGION &
CULTURE
Insects in Mythology
Cultural Entomology
Japanese Culture

22. Although much of the religious and
symbolic significance of insects has
faded in the glare of modern science
and technology,
our language still reflects many
traditional associations:
busy as a bee, annoying as a fly, mad
as a hornet.
We still recognize
the ant as a symbol of hard work, the
lady beetle as a harbinger of good
luck, and
the butterfly as an object of transient
beauty.
LANGUAGE
ANT symbol of hard work
Transient beauty of BUTTERFLY

23. MEDICAL SCIENCE &
TECHNOLOGY
The study of insects, particularly their life
cycles, physiology, genetics, and ecology,
has contributed a great deal to our overall
understanding of biology.
The geneticist's fruit fly (Drosophila
melanogaster) has contributed much to
our knowledge of chromosome structure,
mutation, and sex-linked inheritance.
Law enforcement agencies have
discovered that insects and other
arthropods can furnish valuable evidence
for criminal investigations.

24. By ., Anjali Pramod Umredkar
M.Sc. Zoology ( Entomology )