NC State Extension Publications

Description and Biology

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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 resemble all  black lady beetles.

Imported willow leaf beetles resemble all black lady beetles.

Imported willow leaf beetles on willow.

Imported willow leaf beetles on willow.

Imported willow leaf beetle eggs

Imported willow leaf beetle eggs are laid in small groups.

Imported willow leaf beetle young larvae

Imported willow leaf beetle young larvae feed in groups.

Older imported willow leaf beetle larvae

Older imported willow leaf beetle larvae skeletonize leaves as they feed.

Host Plants

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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!

Residential Recommendation

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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.

References

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For assistance with a specific problem, contact your local Cooperative Extension Center.

This Factsheet has not been peer reviewed.

Author

Professor Emeritus
Entomology and Plant Pathology

Publication date: Nov. 28, 2012
Revised: Sept. 24, 2019

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