Potato leafhoppers have been found throughout the state. Reports of damage have come from central Illinois, and young nymphs have been found on elm at The Morton Arboretum. These leafhoppers attack oak, maple, red mulberry, red bud, cottonwood, birch, apple, dogwood, hawthorn, wafer ash, euonymous, black locust, and cherry.
Red maple is most severely damaged. The expanding leaves at branch tips will be curled and stunted, and they will be mottled with light green, red, and brown. Leaf edges and entire leaves may turn brown or black. Stem growth is greatly reduced. Overall, the damage looks similar to 2,4-D injury. On other host species, leaves may be misshapen, have brown areas, show early fall color, or have stippling (light dots).
Potato leafhopper adults are wedge-shaped, green, and about 1/8 inch long. They fly readily from foliage when approached and are very migratory, making it difficult to find the insects on damaged foliage. They are strongly attracted to lights at night and are small enough to go through the mesh of window screening. You’ll probably recognize these pests as the little green bugs that fly around the newspaper or book you are trying to read during summer evenings indoors.
As nymphs, potato leafhoppers are similar in appearance to adults but are smaller and cannot fly. Even so, nymphs are quite active and will walk sideways to the other side of the leaf when it is inspected, making them difficult to see. Frequently, the only insect parts that can be found are the transparent, cast skins of the molting nymphs.
Landscape trees may not become damaged heavily enough to warrant control once the client is aware of the cause of the damage. Nursery trees and young landscape trees for which vigorous growth is needed will normally warrant control efforts, particularly red maples. Spray with synthetic pyrethroids such as bifenthrin (Talstar), cyfluthrin (Tempo), lambda-cyhalothrin (Scimitar), or permethrin (Ambush, Astro, Pounce) to obtain control. Carbaryl (Sevin) is also effective. Some landscapers and nurserymen have reported that imidicloprid (Merit, Pointer) applied as a soil or trunk injection has also been effective.
(Other contributors to this article: Staff at The Morton Arboretum)