Elm Leaf Beetle

                                                                 
Elm Leaf beetle larvae feeding on an elm leaf.         
Photo: William M. Ciesla
Through: Forestry Images.

Elm leaf beetle adult.
Photo: Clemson Univ. USDA Cooperative Extension
Through: Forestry Images.


 
Elm leaf beetle eggs on the underside of a leaf.
Photo:   John A. Weidhass, Virginia Tech.
Through: Forestry Images.

The larvae usually feed on the underside of the leaves leaving a brown skeletonized looking leaf. The adults feed on all cells through the leaf. The damage done by the insects is generally aesthetic. However, extensive damage can weaken the tree leaving it more susceptible to other insect or disease attack. Spray trees in early spring with Carbaryl, neem, or a pyrethroid insecticide. Early spring control can reduce subsequent generations later in the summer. Good beetle control can be achieved by soil injections of imidacloprid (Merit), an insecticide that is taken in by the roots and moved systemically throughout the tree. Soil injections eliminate the need to find a calm day to spray.

Another problem with the insects occur in the fall when they move into your home to find shelter from the winter. A vacuum cleaner is the best control for the these unwanted house guests. Boxelder bugs, black and red, and twice as large as an elm leaf beetle also move into houses during the late-summer and fall months.

Links:

Colorado State University Cooperative Extension

University of Wyoming - Cooperative Extension Service, publication B-1035 is particularly helpful for tree care. This online publication contains information on: Aphids, Borers, Cottonwood blotch leaf miners, Cytospora canker, Fireblight, Gall makers, Aspen leaf spots, Oystershell scale, Pear slugs, Powdery mildew, and Spider mites.