The Class Insecta

Amit Gupta

Biology

Scott-3

April 01, 2001

Research Project: Class Insecta

Insects are invertebrates in the class Insecta from the phylum arthopoda. Arthropods

include more than 850,000 species and form by far the largest phylum in the animal kingdom,

exceeding in number all the other Phyla combined. The characteristic tough exoskeleton and

jointed limbs are superimposed in a segmental body plan that reflects the evolution of arthropods

from ancestors of the annelid worm. Insects, arachnids, myriapods and crustaceans are the

major groups in this phylum (Nichols). Insects are the largest of this phylum and make up the

largest class of all organisms and are recognized by taxonomist to have nearly one million

recognized species. It is estimated that their are over ten million species still undiscovered.

Because of this the insect orders are thought to be the least well known. Most of which are

beetles and insects in tropical areas. Insects are part of 28 living orders which all have three

body sections, head, thorax, abdomen and six legs and a pair of antenas. They are split in to

two groups, Apterygota and Pterygota, Pterygota can fly while the more primitive Apterygota

cannot (Gale Group).

Insects are all over the world, from the Tropics to the Tundras. They extremely diverse.

While the order Grylloblattodea order of the Orthopteroid Orders thrives in cold icy places, the

Mecoptera Order of the Hemipteroid Orders does best in the tropical areas of the world. Every

Class is different and includes many kinds of insects. So here is the major 23 Orders. Order

Microcoryphia, which include, Bristletails are part of the subclass Apterygota. Bristletails are

jumping insects with long antennae, that are wingless, with very large eyes, a biting mouth, and

three very fine tails. They live among stones or in woods and grass, and feed mostly on algae.

Order Zygentoma is also part of the subclass Apterygota and include Silverfish, and fibrebrats.

Silverfish are wingless, with small eyes, a chewing mouth, they have a long antennae, and three

thin tails. Their flat bodies are covered in silvery scales. Silverfish like to live in warm damp

places, such as under sinks, in bathrooms, and in bookshelves. Order Ephemeroptera are part of

the Pytergota subclass and include Mayflies, Shadflies Adult Mayflies and Shadflies have wings,

chewing mouthparts (which they don't use, because they die before they feed as adults -- usually

within one day), small antennae, and two or three long tails. Larvae can live as long as four

years. Order Odonata is part of the large subclass Pterygota and include Dragonflies As you

should know they have long thin bodies, two pairs of long narrow wings, and very large eyes.

Dragonflies are the best fliers of all insects. They are also predators, feeding on other insects

which they catch during flight. The larvae live in water, and are also hunters. Order Dictyoptera

is part of the advanced Pterygota subclass and include the very successful cockroach.

Cockroaches (Sub-order Blattodea) have flattened oval bodies with wings (but they seldom fly --

they have well developed legs and scurry about), very long antennae that lie back along the side

of the body, large eyes and chewing mouthparts. They are the most successful order due to their

adaptive skills. Order Isoptera is part of the unprimative Pterygota subclass and include

Termites. We all know that Termites are destructive to wood and major pest. They are social

insects, living in colonies and have soft bodies, biting mouthparts, small eyes and short

antennae. Order Orthoptera which are part of the also common Pterygota Subclass include

grasshoppers, locusts, katydids, crickets. Orthoptera insects have long, strong legs which they

use for jumping and two sets of wings. The front set of wings is hardened and used for protection

as well as for flying. Males also use their legs and the rough parts of their wings to make the

characteristic cricket "chirruping" noise. They have large eyes and are very common. Order

Phasmida which are part of the prevalent Pterygota Subclass include all the stick and leaf

insects. Stick and leaf insects have either long, thin, brown bodies that look like sticks, or flat,

green bodies that look like leaves. They are camouflaged for their own protections. Some

species have wings and others do not. They are occasionally on rosebushes and other plants

but, because of their body shape are often hard to see. Order Dermaptera are part of the large

Pterygota Subclass and include Earwigs. Earwigs are skinny bodied with a large pincer-like tail.

Some species have wings (but few fly). The young hatch from eggs and the female adults feed

and protect them until they are independent, which is very unusual for insects. Earwigs feed on

plants, organic waste and other insects. Order Grylloblattodea which is part of