Cottonwood Leaf Beetle (Chrysomela scripta)
From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.
Importance- Adults and larvae defoliate young trees in nurseries, plantings, and natural stands. Heavy and repeated defoliation reduces growth, and deforms and kills young trees.
Look For:
- Sparse or ragged foliage partly consumed. Entire trees may be defoliated so that only leaf petioles and large veins remain.
- Yellow egg clusters on the undersides of leaves.
- Dark brown and white larvae (one-fourth to one-half inch long) in groups on the leaves.
- Black- spotted avoid beetles on the leaves.
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Biology- The number of generations each year ranges from seven in the South to three in the North. All life stages can be found throughout the growing season. The adult female beetles lay eggs in clusters on the undersides of leaves. Newly hatches larvae feed in clusters and skeletonize the leaves; older larvae consume the entire leaf except for the midrib and large veins. Large populations of larvae will also feed on growing shoots and buds. The adult beetles also feed on leaves as well as on the tender bark at the tips of twigs. Adults of the last generation overwinter under leaf debris or in clumps of weeds.
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 Leaf damaged by cottonwood leaf beetlePhoto by James Solomon, USDA Forest Service
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Monitoring- Inspect whips or trees for adult beetles soon after weather warms and thereafter for all life stages. Examine 50 whips of each clone in the nursery; when any clone averages one or two beetles per whip, consider treatment with an approved or registered insecticide. In plantations, treat when trees are 20 percent defoliated.
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Control:
- In heavily infested areas, spray trees thoroughly with an insecticide recommended for leaf beetles. Repeat if populations rise and defoliation continues.
- Plant resistant clones.
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 Egg cluster of cottonwood leaf beetlePhoto by Dennis Haugen
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For Additional Information:
Caldbeck, Elaine; McNabb, Harold S., Jr.; Hart, Elwood R. 1978. Poplar clonal preferences of the cottonwood leaf beetle. Journal of Economic Entomology. 71: 518-520.
Harrell, M.D.; Benjamin, D.M.; Berbee, J.G.; Burkot, T.R. 1981. Evaluation of adult cottonwood leaf beetle, Chrysomela scripta (Coleoptera: Chrysomelidae), feeding preference for hybrid populars. The Great Lakes Entomologist. 14: 181-184.
Neel, W. W.; Morris, R. C.; Head, R. B. 1976. Biology and natural control of the cottonwood leaf beetle, Chrysomela scripta (Fab.) (Coleoptera: Chrysomelidae). In: Thielges, Bart A.; Land, Samuel B., Jr., eds. Proceedings, symposium on eastern cottonwood and related species; 1976 September 28-October 2; Baton Rouge, LA. Baton Rouge, LA: Louisiana State University: 264-271.
Oliveria, F.L.; Cooper, D.T. 1977. Tolerance of cottonwood to damage by cottonwood leaf beetle. In: Proceedings, Southern forest tree improvement conference; 1977 June 14-16; Gainesville, FL. Macon, GA: U.S. Department of Agriculture, Forest Service, Eastern Tree Seed Laboratory; 14: 213-217.
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 Cottonwood leaf beetle larvaePhoto by Gerald J. Lenhard
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 Adult cottonwood leaf beetlePhoto by Gerald J. Lenhard
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