CLASS: Insecta  

Definition: Insects are animals with a bilaterally symmetrical body and that possess a head, a three-segmented body (head, thorax & abdomen), and three pair of thoracic walking legs as adults. Insects have wings at some stage in development, but these are secondarily lost in some species. The circulatory system is open, meaning that blood does not move through arteries and capillaries. The nerve cord is solid and located ventrally.

Insects are the most numerous of known animals, in terms of species. They represent nearly half of all named animals, or about 750,000 species. They are found underground, in the air, in ponds and streams, on our bodies--in fact, in most habitats from the arctic to the tropics. They are, however, conspicuously absent from oceanic environments (though they may be quite abundant on beaches!). 

Insect diversity is astounding. Flies and dragonflies are the most skilled of all flying animals; bees and wasps possess venomous stings; termites and ants live in huge, socially-structured societies; many species are essential plant pollinators; others are vectors for deadly diseases; and few animals can rival the beauty and colors of some butterflies and beetles. 

CLASS: Diptera—Flies, 2-winged insects

CLASS: Hymenoptera—Bees, wasps & ants

CLASS: Coleoptera—Beetles

CLASS: Orthoptera—Grasshoppers & mantids

CLASS: Odonota—Dragonflies

CLASS: Hemiptera--True bugs

CLASS: Homoptera--Aphids, cicadas, leafhoppers

CLASS: Lepidoptera—Butterflies & moths

CLASS: Diptera--Mosquitoes, flies

CLASS: Siphonaptera—Fleas

Links:

Damselfly Website: stephenville.tamu.edu/~fmitchel/damselfly/index.html