Monday, January 14, 2008

Potato Leafhopper

Potato Leafhopper
Empoasca fabae (Harris), Cicadellidae, HEMIPTERA)

Adult - Because many species of leafhoppers look alike, entomologists studying these insects must rely heavily on examination of internal genitalia structures, as well as external morphological characters, to distinguish the various species. The mature potato leafhopper is about 3 mm long, wedge-shaped, and winged. Generally greenish, it has very small, yellowish, pale, or dark green spots, and readily jumps when disturbed.

Egg - About 1 mm long, the egg is elongate and whitish.

Nymph - Several nymphal stages exist, all of which are wingless and smaller than the adult. Though paler, the nymph is colored similarly to the adult.

Distribution - During the summer, potato leafhoppers are found from the Atlantic coast to the Rocky Mountains. They are absent throughout most of the winter which they spend in the Gulf States. Northeastern and midwestern states suffer the greatest forage loss from this pest due to the concentration of alfalfa and clover in these areas. In North Carolina, these leafhoppers are widely distributed during the growing season on peanuts, hay and pasture crops.

Host Plants - This leafhopper feeds on more than 100 cultivated and wild plants, including bean, potato, alfalfa, soybean, and peanut. In North Carolina, peanuts are more seriously affected by this pest than are forage and pasture crops.

Damage - Nationwide, the potato leafhopper is a very injurious pest of forages, particularly alfalfa and clover. Both nymphs and adults feed on the undersides of the leaves. By extracting the sap, they cause stunting and leaf curl, as well as the condition called "hopperburn." This disease is caused by the injection of a toxic substance. It is characterized by a yellowing of the tissue at the tip and around the leaf margin which increases until the leaf dies. Symptoms are sometimes confused with drought stress.

Life History - Potato leafhoppers winter in the Gulf States and migrate northward in spring. They arrive in North Carolina in early summer. After mating, eggs are laid inside the veins on the underside of leaves. A female leafhopper lives about a month, producing one to six eggs daily. Eggs hatch in about 10 days, and the nymphs mature in about 2 weeks. Mating occurs approximately 48 hours after maturation. Three or four generations are produced each year in North Carolina.

When populations become severe, insecticides are the only practical method of leafhopper control.

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