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Insects Main Page |
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The insects (Class Insecta) represent by far the largest single group of living organisms on earth. By some accounts they represent two-thirds to three-fourths of the known species on earth. Some 95,000 described species were listed in Nomina Insecta Nearctica as living in North America north of the Mexican border. The biological, and superficial diversity of the insects is nearly over-whelming, but all insects adhere to a basic morphological ground plan. The body is divided into three main segments: the head, the thorax, and the abdomen. The thorax bears three pairs of jointed legs. The class of insects is sometimes referred to as the Hexapoda for this reason. In common with the rest of the arthopods, insects have an exoskeleton (an external hard shell) and in insects this exoskeleton is composed of chitin. Almost all insects are terrestrial (although many are freshwater aquatics). There are no true marine species, although many species live in salt marshes or along the ocean shore. |
A small group of bugs related to water striders can be found on the surface of the ocean far from land. For more extensive introductions to the insects, you may look at the general sites listed on this page. A list of the orders of insects is given below with links to the respective pages dealing with each order. Some groups of insects are barely covered on the World Wide Web and those without specific sites are followed by the notation (see General Sites). A more thorough classification scheme for the Insects taken from Nomina Insecta Nearctica may be found at this link. Although most groups of insects do not have sites devoted to them, we would particularly invite you to see the extensive and impressive work the Dragonfly and Damselfly workers have compiled on the WWW. Nearctica has a checklist of all 90,000 species of insects found in the United States and Canada. Nomina Insecta Nearctica. A Checklist of the Insects of North America.
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