During the autumn months, homeowners with hackberry trees often become annoyed by large populations of adult jumping plant lice or psyllids. Although they do not bite, sting, carry disease or feed on human possessions, they are a nuisance by their presence, appearing to be attracted to bright colors and night-lights. Usually adult infestations are short-lived. They are wedge-shaped, resembling tiny cicadas and winged aphids.
Nymphs live inside leaf galls throughout the summer months.
There is an interval of 10 to 12 days between egg hatching and gall formation. It is the nymph feeding activity that stimulates abnormal leaf growth, producing the gall that encloses and protects the nymph during its period of growth. Although hackberry leaves are disfigured by numerous galls on the undersides, the growth and vigor of these trees are not retarded to any noticeable extent. One nymph, or immature, is present in each gall. Nymphs mature and then exit the gall once leaves have fallen.