When populations are large, elm leaf beetle larvae and adults can completely defoliate elms. Adults chew small, circular holes. Infested trees appear drought-stricken and brown or scorched. After the beetles feed, only the lacy vein structure of the leaf remains. Leaves quickly turn brown, curl and detach.
Emerald ash borer (EAB) is an Asian beetle that threatens the existence of ash trees throughout North America. These insect pests have killed millions of ash trees in urban areas, woodlots, and nurseries, spreading via infested nursery stock and firewood. Regulatory quarantines rely on public cooperation and can be difficult to enforce. They can slow the spread of EAB, but cannot stop it.