Elm leaf beetles are serious pests that can cause severe damage to elm trees. This leaf beetle prefers Siberian elm and American elm, and will feed, to some degree, on the foliage of Japanese zelkova.
The larvae and adults of the elm leaf beetle can completely defoliate elms when populations are large. Adults chew small circular holes into the tree's leaves. Infested trees appear drought-stricken and scorched brown. After the beetles feed, on the lacy vein structure of the leaf remains. Leaves quickly turn brown, curl and detach.
Management and Treatment
To maintain tree damage caused by the elm leaf beetle, a foliar application should be made when egg hatch is complete, which is sometime in mid-May to mid-June. A second applications may be necessary in mid-July.
In areas where there are multiple generations, monitor elms every 30 days between peak larval occurrences. If beetles have been a nuisance indoors, a late-season foilar treatment in mid-September may reduce the invading swarm. You can also help elms fight off problems if your keep them vigorous with applications of our slow-release fertilizer Arbor Green PRO®.