NC State Extension Publications

Description and Biology

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The cottonwood leaf beetle, Chrysomela scripta, feeds on the leaves of willow, poplar, and alder throughout North Carolina. Adults are the overwintering stage and survive the winter to emerge in early spring and feed on the buds, tender new leaves, and tender bark. Tiny yellow eggs are laid in masses of 15 to 75 on the lower leaf surface. Black, tiny, new larvae hatch and feed in groups. Young larvae skeletonize the leaves. As they grow, older larvae separate and consume entire leaves except for the midrib. Older larvae are grayish brown with two rows of conspicuous pale spots down the back. After feeding for about 2 weeks, the larvae pupate on the leaves, stems, trunk, and nearby objects. A new generation of adult beetles emerges in 5 to 10 days. Several generations occur each year.

cottonwood leaf beetles

Cottonwood leaf beetles feed on willow and cottonwood.

cottonwood leaf beetle larvae

Cottonwood leaf beetle larvae often feed in groups.

Older cottonwood leaf beetle larvae have conspicuous pale spots.

Older cottonwood leaf beetle larvae have conspicuous pale spots.

Cottonwood leaf beetle pupae are very dark.

Cottonwood leaf beetle pupae are very dark.

Host Plants

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Cottonwood leaf beetles feed on cottonwood, aspen, poplar and willow throughout North Carolina. The tiny new larvae feed in groups and don't eat much. Young larvae skeletonize the leaves. As they grow older, the larvae separate and consume entire leaves except for the midrib.

Residential Recommendation

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Lady beetles and their larvae feed on cottonwood leaf beetle eggs and pupae (cottonwood leaf beetle larvae have a defensive secretion that is effective in repelling predators. A few kinds of predatory stink bugs feed on the beetles. If cottonwood leaf beetles cause noticeable defoliation and if a tree is small enough to treat, various pyrethroid and other insecticides are available in most garden centers. Be sure to follow the directions on the label of whichever pesticide is used.

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This Factsheet has not been peer reviewed.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. 19, 2012
Revised: Sept. 12, 2019

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