Harmful symptoms:
Adults and larvae feed on leaves in notches or holes.
Occurrence law:
(1) generation. There are 4 ~ 5 generations a year in Henan and 5 ~ 6 generations in Beijing. (2) Overwintering and insect source: Overwintering with adults in soil, fallen leaves and weeds.
Living habits:
Every April, when the willows germinate, they come out to harm the bud leaves and lay eggs in piles on the leaves. Each female lays more than 1000 eggs for 6-7 days. The newly hatched larvae gather together to do harm and eat mesophyll. The larval stage is about 10 day, and the mature larvae pupate on the leaves. In mid-September, both adults and larvae can be seen, and they have suspended their lives.
Preventive and control measures:
(1) chemical control. Spraying 20% chrysanthemum hemp EC 2000 times or 50% phoxim EC 1000 times, 50% malathion EC 1000 ~ 1500 times and 20% insecticide WP 2000 times.