any member of the approximately 2,000 species of the insect family Psyllidae (order Homoptera). The jumping plant louse is about the size of a pinhead. Its head, long antennae and legs, and transparent wings resemble, on a reduced scale, the features of the cicada. Eggs are deposited on leaves or twigs of the host plant; the nymphs, flattened and broadly ovate, usually feed clustered together. Some species are covered with wax; others produce galls on the host plant.

When the insects are abundant, the honeydew (a sweet by-product of digestion) they excrete forms a film over leaves and branches, sometimes dripping from the foliage like rain. The copious, sweet, waxy secretion of the Australian sugar lerp insect has been collected and eaten by Aborigines. The apple sucker (Psylla mali) and the pear sucker (P. pyricola) are injurious to the plants they infest; the nymphs damage blossoms and shoots and cause a plant's leaves to shrivel.