Hemimetabolous 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 by some authors larvae.
Holometabolous insects (
Endopterygota or
Holometabola) have a four-stage life cycle: egg, larva, pupa, and adult (imago).
Neuroptera - Antlions - Lacewings and allies
Megaloptera - Alderflies, Dobsonflies, and Fishflies
Hymenoptera - Ants, Bees, Wasps and Sawflies
Mecoptera - Scorpionflies, Hangingflies and Allies