Description and Biology
The imported willow leaf beetle, Plagiodera versicolor, resembles a black lady beetle. (Lady beetles are in a different family, and the black ones usually have orange spots of some sort.) Adult imported willow leaf beetles overwinter outdoors and emerge from their hibernation sites in spring. They feed for a while before females begin to lay eggs. Soon larvae hatch and all stages of the beetle can be found. Both stages feed on foliage of willows during the summer. At least two generations occur each year.
Imported willow leaf beetles attack the foliage of willows, cottonwood, and poplar (not tulip poplar). Adults notch and chew holes in the leaves, and their larvae skeletonize the leaves. From a distance, infested trees gradually turn off color and the tree may eventually appear to be dead. Although complete defoliation of a willow is not fatal, it's not good for it either!
One reason the beetles seem to come back after treatment is that pesticides may not kill the eggs so that after treatment additional larvae hatch to carry on the family tradition. Another reason may be that the beetles do not all emerge from their hibernating quarters on the same day. Thus, the trees may be reinfested after the treatment. Mavrik, Merit, permethrin, pyrethrins, Sevin, and Talstar are all labeled for beetle control in the landscape.
- Biology and Management of Insect Pests in North American Intensively Managed Hardwood Forest Systems. Coyle, D. R. et al. 2005. Annual Rev. of Entomology 50: 1-29.
- Imported Willow Leaf Beetle, Plagiodera versicolora (Laicharting); Family: Chrysomelidae. Klass, C., W. T. Johnson, and P. A. Weston. 2012 (update). Insect Diagnostic Lab. Cornell University, Dept. of Entomology.
- The biology of the imported willow leaf beetle, Pagiodera versicolora (Laicharting). Wake, M. J. 1994. Pages 541-547 In Novel Aspect of the Biology of Chrysomelidae. Jolivet, P. H., M. L. Cox and E. Petitpierre editors.
- Extension Plant Pathology Publications and Factsheets
- Horticultural Science Publications
- North Carolina Agricultural Chemicals Manual
For assistance with a specific problem, contact your local Cooperative Extension Center.
This Factsheet has not been peer reviewed.
Publication date: Nov. 28, 2012
Revised: Sept. 24, 2019
North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status or disability. In addition, the two Universities welcome all persons without regard to sexual orientation.