leafhopper, common name for small, wedge-shaped leaping insects, cosmopolitan in distribution, belonging to the family Cicadellidae, which comprises some 5,500 species of insects. Some are brightly colored and others are green to brown; they generally measure less than 1/4 in. (6 mm) in length. Leafhoppers, and the family as a whole, attack a wide range of trees, shrubs, grasses, and forbs. However, the nymphs and adults frequently suck the sap of only one or a few kinds of plants. Besides stunting plant growth by causing loss of sap, some leafhoppers introduce a toxin into the plant as they feed; others introduce disease organisms.
The potato leafhopper, Empoasca fabae, is a serious pest in the E United States. It causes a disease commonly known as hopperburn on potatoes and damages many other plants, including apples, beans, and clover. As a result of the potato leafhopper's attack, the leaf's conducting tissue is plugged; the plant leaves curl and begin to turn brown near the tip, and eventually the whole leaf appears blighted. As many as 5 to 6 million leafhoppers may be found per acre. Other leafhopper pests include the beet leafhopper, which causes the beet disease known as curly top in the W United States; the grape leafhopper; the rose leafhopper; and the apple leafhopper.
Many leafhoppers have a single generation per year, but there may be several. They overwinter either in the adult or egg stage, depending on the species. Eggs are laid singly or a few at a time in stems and leaves. The adults overwinter only in the south; those migrating north each year cause much damage, but are usually killed by the frost.
Leafhoppers are classified in the phylum Arthropoda, class Insecta, order Homoptera, family Cicadellidae.