Recent warm weather has brought out strange behavior in local inhabitants: invasions of elm leaf beetles.Adult beetles thought they were done hibernating, and came out of their cozy over-wintering nooks. In search of juicy elm leaves, they detoured into area houses, causing alarm, but no damage.

El Paso County Extension Agent Catherine Moravec reports several people have had 10 to 20 beetles enter their homes. Some callers reported masses of the beetles on the sunny side of their garden sheds.

Elm leaf beetles are the most common leaf browsers found in Colorado trees. The adults chew circular holes in elm leaves. When the grub-like larvae hatch in June, they chew on the underside of elm leaves, in between the leaf veins, rendering an easily-recognized “skeletonizing” pattern.

Beetles that emerged prior to our recent snowstorm are not likely to survive, a boon to the large elms that line many streets in El Paso County.

Click here for the Colorado State University elm leaf beetles fact sheet.

-For answers to your horticultural questions, contact the Master Gardener Help Desk at 636-8921 or CSUmg2@elpasoco.com.

An adult elm leaf beetle (Pyrrhalta luteola) chews into an elm leaf. Photo by Photo courtesy of Clemson University-USDA Cooperative Extension