incomplete metamorphosis, a type of postembryonic development in insects of several systematic groups (such as dragonflies, mayflies, stone flies, Orthoptera, and Hemiptera). From the eggs come larvae (nymphs), which outwardly are similar to mature insects in that they have faceted eyes and a jointed tarsus, as well as mouth organs just as an adult does. Various orders of insects in the post-embryonic stage have from three to 30 nymph stages. Metamorphosis of the nymph into an adult insect takes place without the chrysalis stage. Sometimes the term “hemimetabolism” is used only for the development of the dragonfly, mayfly, and stone fly, which in the nymph stage have provisional or temporary organs (branchiae, masks); the development of other insects with incomplete metamorphosis, in which the larvae lack provisional organs, is called “paurometabolism.” The opposite of hemimetabolism is holometabolism.
M. S. GILIAROV