Elm Leaf Beetle- Holes in elm leaves

Identification

Elm leaves have many holes in them, but the veins stay intact. Larvae scrape away leaf tissue, leaving a thin layer of leaf tissue. Adult beetles are yellow with a black outline. Larvae are worm-like with yellow and black segments. Yellow egg masses can sometimes be seen on leaves.

Life Cycle

Adults emerge in spring after spending the winter hiding in protected areas. They feed and mate, at which time their wing color changes from green to yellow. They begin to lay egg masses on leaves several weeks after mating. Larvae hatch and begin feeding which ensues for about 3 weeks. Larvae crawl to the trunk to find a pupation site. After adults emerge, individuals either mate and produce a second generation, or move to an overwintering location.

Damage

Damage is caused by both adults and larvae. Adults chew holes through leaf tissue, but leave leaf veins intact. Larvae also feed between leaf veins leaving a thin layer of leaf tissue behind which creates transparent spots in leaves.

Management

There are multiple systemic applications and foliar sprays that can be made to manage elm leaf beetle. Trunk banding (insecticide contaminated band) can also be an effective control since larvae crawl down the trunk to pupate.

See the link below for more information on elm leaf beetle:

http://www.ext.colostate.edu/pubs/insect/05521.html