Incomplete metamorphosis is the gradual development of an insect into its adult stage. It is characterized by the absence of the pupal stage which exists in complete metamorphosis. Complete metamorphosis, such as what a butterfly goes through, involves four stages: egg, larva, pupa and adult. Incomplete metamorphosis varies in that it only involves three stages: egg, nymph and adult.
The first stage of incomplete metamorphosis is the egg stage. The female insect lays the eggs. The eggs are sometimes contained in an egg case that keeps them together and protected. The earliest development happens during this stage; the insect takes form and will usually develop everything except the wings. The gestation period for the eggs varies greatly depending on the variety of insect.
When the eggs hatch, the nymphs emerge. Nymphs look like small adult insects but they are lacking wings, and organs may still be underdeveloped. Nymphs will eat the same diet as their adult versions. As they grow and developt they will go through periods of molting, where they shed their exterior skeletons and grow new ones. Nymphs generally molt four to eight times in their growth cycle.
Once nymphs have reached their full development in terms of size, they will stop the molting process. At this stage they are now fully formed adult insects. During their molting process, insects that have wings will have also grown wings. The length of life of an adult insect varies by species.
Types of Insects
Complete metamorphosis is the more common form of metamorphosis for insects; only about 12 percent of insects go through incomplete metamorphosis. These include head lice, stinkbugs, earwigs, crickets, grasshoppers, cockroaches, true bugs, dragonflies, cicada, ants and praying mantids.