This document discusses insect morphology and classification. It defines entomology as the study of insects and notes they have three body segments and three pairs of legs. Major classes of arthropods are described including characteristics of orders like Apterygota, Pterygota, Hemiptera, Odonata, Orthoptera, Isoptera, Coleoptera, Diptera, Lepidoptera, and Hymenoptera. Insect leg types are outlined including cursorial, saltatorial, raptorial, natatorial, and fossorial. Metamorphosis is defined as the physical development of an animal after birth/hatching.

1. Entomology
Orders Of Insects
Insect's Legs
By Muhammad Rehan
BS Forestry
University Of Swat
+923469792050
ForesterRehanUOS@Yahoo.Com

2. Entomology
• Entomology is defined as the study of
insect
• Insect are those creatures which have
three pair of legs and the body of which is
divided into three segments i.e head,
thorax and abdomen

3. Characteristics of arthropoda
• They have chitinous exoskeleton that shed
during growth
• Paired appendages i.e legs and antenae
are jointed
• Segmented body
• Bilateral symmetry
• Open circulatory system

4. Major classes of arthropoda
Crustacean: Five or more legs, two antenae
Wings absent i.e crabs
Myriapoda: Many legs, one or two per
segment
Wings absent i.e milipede and centipede
Arachidae: Four pair of legs, No antenae,
Wings absent i.e ticks, mites and scorpion
Insecta: Have head, thorax and abdomen,
three pair of legs, paired antennae, wings

5. Apterygota
• The name Apterygota is sometimes applied to a subclass of small,
agile insects, distinguished from other insects by their lack of wings
in the present and in their evolutionary history. Their first known
occurrence in the fossil record is during theDevonian period,
417–354 million years ago.
• The nymphs (younger stages) go through little or even
no metamorphosis, hence they resemble the adult specimens. Their
skin is thin, making them appear translucent.
• Currently, no species are listed as being at conservation risk.
• Characteristics of Insect Class Apterygota
• 1. Wings are primarily absent.
2. Metamorphosis is absent / slight.
3. Adults possess one or more pairs of pregenital appendages.
4. Mandibles are articulated at single point. E.g. Bristle tail, Silverfish,
Proturans, Diplurans, Japyx, and Spring tails.

6. Pterygota
• The Pterygota are a subclass of insects that includes the
winged insects. It also includes insect orders that are
secondarily wingless (that is, insect groups whose ancestors
once had wings but that have lost them as a result of
subsequent evolution).[1]
• The pterygotan group comprises almost all insects.
The insect orders not included are
the Archaeognatha (jumping bristletails) and
the Thysanura (silverfishes and firebrats), two primitively
wingless insect orders. Also not included are the three orders
no longer considered to be insects: Protura, Collembola,
and Diplura.
• Characteristics of Insect Class Pterygota
• 1. Adults are winged or secondarily wingless.
2. Metamorphosis is always present.
3. Adults do not moult and do not have pregenital appendages.
4. Mandibles are articulated with head capsule at two points.

7. Order hemiptera
• Characteristics
The insects in this order are extremely diverse in their size, shape and colour.
The name Hemiptera means 'half wing' and all hemipterans share the following
features:
•
2 pairs of wings, although some species may be wingless and others have only
forewings. Wings are generally membranous but in some species the forewings
may be hardened at the base
• Piercing or sucking mouthparts appearing as a sharply pointed tube known as
a proboscis or rostrum, which extends from the underside of the head
• Compound eyes of various forms
• Antennae vary and may be either short, or long and conspicuous
• The young of hemipterans look like small adults. Some bugs may be mistaken
for beetles but can be distinguished by their mouthparts as beetles
have mandibulate mouthparts while bugs have sucking/piercing mouthparts.
• Hemiptera: bugs, aphids and cicadas

9. Important orders of insects
• Order Thysanura
• The silverfish and firebrats are found in
the order Thysanura. They are wingless
insects often found in people's attics, and
have a lifespan of several years. There are
about 600 species worldwide.

10. Order Odonata
• Two physical features identify most members of
the order Odonata - extremely large eyes (in
proportion to its head) and a long, slender
abdomen.
• Odonates are predacious as naiads and adults.
Dragonflies and damselflies have tiny antennae,
so vision is their primary means of navigating and
capturing prey. Odonates can rotate their heads
nearly 360 degrees, giving them an almost
limitless field of view.
• Several differences in wing structure separate the
Odonates from other insect groups.

11. Cont..
• Odonate eggs are laid in water, where
they hatch into wingless naiads. The
naiads have gills, and will molt up to 15
times, depending on the species. Some
naiads remain in their aquatic environment
for as long as two years before reaching
adulthood. The final molt produces
functioning wings, and the adult dragonfly
or damselfly can hunt over water or land.

12. Order Orthoptera
• These are familiar insects - grasshoppers,
locusts, and crickets - and one of the
largest orders of herbivorous insects.
Incomplet metamorphosis. Nymphs look
similar to mature adults, but lack fully-
developed wings.

13. Cont..
• Powerful hind legs built for jumping characterize
the Orthopteran insects. The muscular legs
propel grasshoppers and other members of the
order for distances up to 20 times their body
lengths.
• Insects in the order Orthoptera are known for
more than their jumping skills, however. Many
are accomplished singers as well. Males of
some species attract mates by producing
sounds with their legs or wings. This form of
sound production is called stridulation, and
involves rubbing the upper and lower wings or
the hind leg and wing together to create a
vibration.

14. Isoptera
• These social insects feed on the cellulose
in wood and wood by-products, including
the structural lumber of buildings. Termites
of the order Isoptera first appeared over
250 millions years ago. The name Isoptera
means equal wing; primary reproductive
adults have two pairs of wings, equal in
length.

15. Cont…
• Isopterans play a major role in decomposition on the
planet.
• They have pale, elongate bodies, and are sometimes
called “white ants.” Reproductive individuals have two
pairs of membranous wings, all of equal length.
Termites shed their wings after mating. To consume
fibrous plant matter, termites have chewing
mouthparts.
• Their antennae are roughly the length of their heads.
• As with honeybees, the termite queen controls
reproduction. However, in the termite world, the male
reproductive or king, stays with the queen and
continues to fertilize her eggs for life.
• Termites undergo simple metamorphosis.

16. Colleoptra
• Beetles have hardened forewings, called
elytra, which protect the delicate hind wings
folded beneath them.
• Beetles feeding habits are widely varied, but
all have mouthparts adapted for
chewing. Many beetles are herbivores,
feeding on plants.
• Predatory beetles attack other invertebrates
in the soil or vegetation. Parasitic beetles
may live on other insects, or even mammals.
A few beetles scavenge decaying organic
matter or carrion.

17. Diptera
• Diptera is one of the largest orders, with
nearly 100,000 insects named to the order.
These are the true flies, mosquitoes, and
gnats. Insects in this group have modified
hindwings which are used for balance
during flight. The forewings function as the
propellers for flying

18. Order Lepidoptera
• The butterflies and moths of the order
Lepidoptera comprise the second largest
group in the class Insecta. These well-
known insects have scaly wings with
interesting colors and patterns. You can
often identify an insect in this order just by
the wing shape and colo

19. order Hymenoptera
• The order Hymenoptera includes many of
the most common insects - ants, bees,
and wasps. The larvae of some wasps
cause trees to form galls, which then
provides food for the immature wasps.
Other wasps are parasitic, living in
caterpillars, beetles, or even aphids. This
is the third largest insect order with just
over 100,000 species.

20. Insect legs

21. Insect leg cont..
• Three pairs of jointed legs are virtually
always present in adult insects and each
leg is normally comprised of five major
segments: coxa, trochanter, femur, tibia
and tarsus. The tarsus may be further
divided into 2-5 smaller segments called
tarsomeres, the last of which may bear a
pair of claws.

22. Insect leg cont..
• In some insects, pads (pulvilli) located
beneath the claws enable them to have
greater purchase on smooth surfaces. This
may be enhanced by densely packed small
hairs on the pulvilli and in some species, like
the house fly, these hairs exude a sticky
secretion that permits them to walk vertically
up a smooth surface such as a window pane
and upside down on a ceiling.
• The coxa is attached to the thorax and the
leg segments are attached to each other by
intersegmental membranes at the joints.

23. Types of insect leg
• 1. Cursorial legs. These are the types of
legs most people likely think of if they’ve ever
pondered insect legs before. Cursorial is a
fancy word for running, so these are the
kinds of legs you see on swiftly moving
insects such as roaches and tiger
beetles. Cursorial legs tend to be long and
narrow and are designed so that the insect
can move very quickly. Things with this type
of leg are often hard to catch – or hard to
step on if you’re dealing with roaches.

24. Cursorial

25. Saltatorial legs.
Saltatorial legs are jumping legs. You’ve all
seen these kinds of legs before! Grasshoppers
are the poster insects for saltatorial legs, but
other jumping insects like fleas have them as
well. Saltatorial legs work well for jumping
because they are enlarged legs filled with bulky,
strong muscles. All those muscles allow
insects with this type of leg to jump, propelling
themselves forward very long distances very
quickly. Saltatorial legs are usually hind legs.

26. Saltatorial

27. Raptorial legs.
• You are likely familiar with this sort of leg
too. Raptorial legs are hunting legs, the
kinds of legs you see on predatory insects
such as mantids and giant water bugs. Like
the saltatorial legs, these are enlarged legs
full of strong, powerful muscles. However,
these legs are usually at the front of the
insect and are used to grab and hold prey
while they eat. Many insects with raptorial
legs hold them out in front of their bodies,
positioned so that they can strike at prey at
any time.

28. RAPTORIAL

29. Natatorial legs.
• Natatorial is another word for swimming, so
insects with natatorial legs are aquatic insects that
require modified legs to move easily through
water. Natatorial legs are often flattened, broad,
and fringed with dense hairs, as in the image of
the predaceous diving beetle hind leg pictured at
right. These adaptations have the same sort of
effect as a human wearing flippers as they swim –
they increase the surface area of the legs as they
kick, allowing the insect to move more easily
through water. Many aquatic insects exhibit
natatorial legs, especially in the hind and middle
pairs of legs, but not all of them do. They are
especially common in aquatic beetles and bugs.

30. NATATORIAL

31. Fossorial legs.
• Insects with fossorial legs live underground
and use their highly modified legs, usually the
forelegs, to dig burrows. The mole cricket,
the forlegs of which are pictured at left, are a
prime example. Fossorial legs tend to be
very broad, very flat, and very dense. They
often have big, strong claws. Fossorial legs
work somewhat like shovels to rip soils apart
quickly and easily and allow the insect to
bury itself in the ground surprisingly quickly.
This type of leg is much less common than
the others, but it’s a thrill to find an insect that
has them

32. FOSSORIAL

33. Metamorphos
• Metamorphosis is a biological process by
which an animal
physically develops after birth or hatching,
involving a conspicuous and relatively
abrupt change in the animal's body
structure through
cell growth and differentiation
• Insect can be divided into species that
undergo complete metamorphosis
("holometaboly"), incomplete
metamorphosis ("hemimetaboly"), or no
metamorphosis ("ametaboly")