It pays to know what insects look like throughout their life cycle, because they change form as they grow in a process called metamorphosis. Born with rigid or semi-rigid outer skins, insects would have a difficult time growing if they were not able to shed this covering as they outgrew it. Some insects—such as beetles, lacewings, and moths—start life as larvae and evolve to an intermediate stage called pupae. After more molting, they assume their adult form, which looks completely different from the earlier stages. This is a complete metamorphosis.
Most people are familiar with the caterpillar-to-butterfly cycle, but many people are not aware of what lady beetles and lacewings look like in infancy. During this larval stage, these and some other beneficial insects, have an especially voracious appetite for pests. Unfortunately, for these helpful bugs, they are considered ugly as larvae, and so unlike their familiar adult forms, unknowing gardeners often squash them.
Other insects do not experience the same degree of transformation, and go through a gradual metamorphosis. In the immature stage, these “nymph” insects look like smaller versions of their adult forms. Mantises and aphids are examples of such insects.