Potato leafhopper, Empoasca fabae, damage has been noticed in central Illinois, with populations numerous in southern and central Illinois. Potato leafhoppers attack many ornamental landscape trees, including crabapple (Malus spp.), birch (Betula spp.), ash (Fraxinus spp.), and maple (Acer spp.). Red maples are extremely susceptible, whereas silver, sugar, and Norway maples are tolerant.
Potato leafhoppers have piercing–sucking mouthparts, which they use to feed within the vascular tissues (primarily the xylem) of plants. During feeding, they inject a toxic substance into plant tissues. Feeding, especially on maples, results in stunted tree shoots and leaves that curl downward, with brown edges. This damage looks as if the infested trees have been sprayed with a phenoxy-based herbicide (that is, 2,4-D). On plants such as ash, feeding creates small, white or yellow spots on leaves. This results in a stippled appearance that resembles twospotted spider mite injury; potato leafhoppers, as do twospotted spider mites, remove chlorophyll (green pigment) from leaves. Potato leafhoppers don’t overwinter in Illinois because their eggs are sensitive to the cold. From the Gulf of Mexico (nice place to overwinter), adults are blown north into Illinois by prevailing winds from early May to early June.
Potato leafhopper adults settle into alfalfa fields during the spring migration; and after the first cutting of alfalfa, they migrate onto ornamental trees. Adults are about 1/16 inch long, wedge-shaped, and pale green, with white eyes. Females lay eggs in the veins on the leaf underside. Eggs hatch in 6 to 9 days into light green nymphs that are found on the underside of leaves and tend to move sideways when disturbed. Nymphs may undergo five instars before molting into adults. Adults and nymphs look similar except that the adults are larger, have wings, and can fly. The wings are held rooflike over the body. Empty, white, cast skins on the underside of leaves provide evidence of potato leafhopper activity. There may be as many as three to five generations per year in Illinois.
Insecticides must be applied before potato leafhoppers cause severe plant damage. Applications of pyrethroid-based insecticides such as bifenthrin (Talstar), cyfluthrin (Tempo), lambda-cyhalothrin (Scimitar), and permethrin (Astro) generally provide adequate control. If plant damage has already occurred, insecticide applications prevent further damage, and new growth appears normal beyond the damaged leaves. Regular scouting helps minimize the potential for potato leafhoppers to cause severe foliar damage.