In this case, control measures would be necessary. Damage appears to be more frequent in areas bordered by turf or pasture, since these are also feeding grounds for the beetle grubs. Leafhoppers damage leaves by sucking out the liquid contents of cells. The potato leafhopper usually shows up in June on Long Island. It can be found on leaf undersides and moves sideways when disturbed.
Damage appears as a marginal yellowing of the leaf.
The grape leafhopper is similar in appearance, but has 3 black spots and does not move sideways. Damage appears as a yellow speckling, especially along veins. Growers do not usually treat for leafhoppers. Aphids , another group of sucking insects, are a common pest on many plants. In some years, the dark brown grapevine aphid has literally blanketed shoot tips of vines.