Class Insecta - Insects

From Latin insectum (plural insecta) for "cut into, cut up". This refers to the way the joints between body segments are marked by an indentation as if carved by a chisel. The word probably arose as a literal translation of Greek entomos (εντομος), which has the same meaning.

Worldwide: (1)

U.S. & Canada: (2)

Nearctica.com lists 34 orders.

Anatomy

See figures:

   

See BugGuide Glossary for terminology.

See Overview of Orders of Insecta--an illustrated guide to the orders of insects.

Throughout North America, and worldwide.

There are two prominent types of life-cycles among the insects:

1-Hemimetabolus insects (e.g., dragonflies, mayflies, true bugs, grasshoppers) undergo gradual, or incomplete, metamorphosis. Immature stages (usually called nymphs) go through a series of molts, gradually assuming an adult form. Since the wings develop on the outside of the body, these groups are called exopterygotes. Some orders have immature stages that are aquatic. These possess specialized structures for aquatic life, such as gills, and are called naiads, or larvae.

2-Holometabolous insects have a four-stage life cycle: egg, larva, pupa, and adult (imago). The following orders of insects are holometabolous:

This group is referred to as Endopterygota or Holometabola.

The Pterygota--winged insects--were formerly considered a subclass of Insecta--see the linked glossary entry for more information.

Note on taxonomic sequence of insects

The sequence of orders of winged insects used in BugGuide follows, mostly, that used in Arnett, American Insects (2). There has been some disagreement about the sequence of orders in Insecta presented here. It has been the consensus both in the 2006 discussion and the 2007 discussion NOT to use an alphabetical sequence for the orders, because this places related groups far apart. Please discuss before making changes. As an organizational aid, see the alphabetical list below.

Alphabetic list of Pterygota orders