Factors which can affect catch include the existence of nearby wild apple or hawthorn or the level of maggot infestation in your own orchard last year. When scouting, be sure to check for mite predators such as Amblyseius fallacis , Stethorus punctum , and Zetzellia mali . I would expect to find them in orchards where multiflora rose is abundant around orchard borders. The older nymphs of RLH can be separated from the WALH because large RLH nymphs have spots on their backs, while large WALH nymphs do not. Our treatment threshold is 1 WALH or RLH per leaf.
Pesticides are most effective on young nymphs and least effective on adults.
Even if this generation of RLH is controlled, there is still another generation of WALH expected in August and September. Unless RLH populations are high, it might be better to treat for leafhoppers when both species are present in August. PLH adults and nymphs are yellowish-green and similar in size and shape to the white apple and rose leafhoppers. They are usually not a problem on large, established trees, but can cause stunting of growth on young trees. Symptoms of PLH feeding include a downward cupping of leaves, marginal leaf yellowing and a shut down of shoot growth.