However, hopperburn symptoms result from the plant's response to the feeding. Therefore, responding to the damage by spraying is not the best option. It does help, because new leaves will be free of injury. But the best management is to scout for leafhoppers. It is easy to do with a sweep net, or by closely examining the undersides of leaves.
Adults also have a characteristic deep lime-green color.
Scouting and spraying when thresholds are exceeded is the best management. In some states, the early season influx is monitored simply by regional reporting of the scouting data from alfalfa. Pennsylvania State University.