As day length shortens in August to less than 14 hours, adult beetles stop producing eggs. They then feed for a short while and seek overwintering shelter. Natural Controls Few natural enemies feed on elm leaf beetles. Pupae may be killed by a small wasp that develops in the Insects. Small numbers of pupae also may be killed by fungus disease.
Weather probably is the most important factor that affects elm leaf beetle populations.
Long winters or a late spring freeze may kill large numbers of overwintering beetles. Small larvae are susceptible to being blown or rubbed off trees during wind storms. This may be particularly common when larvae are forced to feed on older, tough leaves. This increases their wandering and many die in the process. Control on Trees insecticides Several insecticides are effective controls when sprayed on foliage at the proper time in the life cycle.