This past week (late May) our field scouts and I started seeing the first pale green potato leafhoppers (PLH) in the field, right about on schedule. They saw them on potatoes and beans while I spied them on tender growth of our English walnut tree, a sentinel at the north end of a long open field that often intercepts early adults arriving on southern breezes. The insect is a snowbird, migrating north each spring from Florida to Louisiana around the Gulf Coast, with later generations returning as cold fall weather sets in. There are indications some survive winter even further north but the flood of migrants from more southern areas on warm winds seems be the main vehicle for re-introduction.
Every year is different: there may be high numbers in one year followed by very low populations the next. We haven't yet been able to predict in advance what we are in for, but crop growers pay close attention to spring reports, as infestations can dramatically reduce potato, bean and alfalfa yields following appearance of 'hopperburn' symptoms characteristic for this insect. These appear a week or so after infestation and include leaf and shoot stunting, leaf yellowing, curling/distortion and edge burn due in part to a toxin the insect secretes into the plant when feeding. The damage looks similar to that caused by high soluble salts from excess fertilizer. Grape, strawberries, apples, hops, hemp and clover are among other crops affected.
Among ornamental plants dahlias are high on the list of preferred hosts, sometimes dramatically injured; I've also seen the leafhoppers (and hopperburn) on astilbe, rose, lupine, wisteria, hibiscus, Baptisia, birch, redbud, walnut, oak, and maple. The list of susceptible ornamentals is undoubtedly longer – over 200 plants are hosts, though some are reportedly only suited to adult leafhoppers and don't support immature stages.
Read more at e-gro.org