views updated

heteromorphosis (hypermetamorphosis) Development in which there is a radical change in form between successive larval instars. For example, the tiny insects of the order Strepsiptera have an active first-instar larva (called a triungulin), which is succeeded by several inactive, often legless, grublike larval stages. This change in form reflects quite different functions. The triungulin's task is to seek out a suitable larval host, which is then parasitized by the following inactive larval stages.