The scale-like nymphs lose their legs after the first molt and are occasionally referred to as larvae. A resting stage, known as the pupa, precedes adult emergence. Whiteflies regain their legs as adults. These insects do undergo gradual or simple metamorphosis even though names assigned to the various life stages are analogous to those of complete metamorphosis. Another family of tiny insects, the Aphididae contains winged and wingless forms.
Color varies greatly among species.
Wingless adult females produce young without mating and, therefore, large populations often develop rapidly. All aphids, both adults and nymphs, extract plant sap. Larger than aphids and whiteflies, spittlebugs may be up to 13 mm long. The brown, black, or gray adults are jumping insects which do not attract as much attention as the nymphs. Enveloped in a white, frothy mass resembling spittle, brightly colored nymphs suck sap from plants and sometimes transmit plant diseases.