NC State Extension Publications

General Information

CAUTION: This information was developed for North Carolina and may not apply to other areas.


The elm leaf beetle, Xanthogaleruca luteola, is about 316 inch long with darker outer margins of the wings and several black spots on the head and thorax. Eggs are about 132 inch long and are yellow and spindle-shaped. The newly hatched larva is nearly black. Larger larvae are yellow with black bumps. Full-grown larvae are yellow with black stripes along each side. Larvae have a proleg at the rear used for walking. Elm leaf beetle pupae are yellow to bright orange and are usually found in litter on the ground.

Elm leaf beetles

Elm leaf beetles occasionally cause noticeable defoliation of elms.

Female elm leaf beetles usually lay their eggs

Female elm leaf beetles usually lay their eggs on the undersides of leaves.

elm leaf beetle larvae

Older elm leaf beetle larvae are yellow with black sides.

Elm leaf beetle larvae climb down to pupate around elms.

Elm leaf beetle larvae climb down to pupate around elms.

Elm leaf beetle pupae are yellow to orange.

Elm leaf beetle pupae are yellow to orange.

Biology

The elm leaf beetle was introduced from Europe in 1838 and is now found throughout the United States. Elm leaf beetles overwinter as adults. As the buds on elms start to swell in spring, the beetles begin to emerge. Females begin laying eggs in late May and over the next several weeks, deposit 400 to 800 eggs each in clusters of two or three rows. Eggs are usually placed near the midrib on the underside of leaves. About a week later, they hatch into tiny larvae that skeletonize the leaves by feeding on the lower surface but leave a thin layer of the upper surface intact. The larvae mature in two or three weeks at which time they drop to the ground to pupate under litter or some other shelter near the base of the tree. A new generation of adults emerges in about ten days. Many of the beetles that emerge during the summer months seek places for hibernation early in the season. This movement toward shelter continues until cool weather. In fall, adults may be a nuisance as they crawl into buildings seeking an overwintering site. We have two generations per year in the mountains and three generations in the Piedmont and Coastal Plain.

Host Plants

Elm leaf beetles feed on all elms but tend to prefer English, American and Chinese elms. Zelkova is fed upon less frequently. Damage is most noticeable in landscape trees. The elm leaf beetle is consider the most serious elm defoliator in the United States. Larvae skeletonize leaves which then turn brown and may defoliate prematurely. Adults chew irregular holes in the leaves. Heavily infested trees may be weakened or even killed after repeated attacks.

Elm leaf beetle larvae skeletonize elm leaves

Elm leaf beetle larvae skeletonize elm leaves. Damaged leaves die and drop prematurely.

Elm leaf beetles sometimes cause extensive defoliation.

Elm leaf beetles sometimes cause extensive defoliation.

Management

Few natural enemies feed on elm leaf beetles perhaps because it is an introduced species and left most of its natural enemies behind. Predaceous stink bugs and plant bugs feed on various stages of the elm leaf beetle. Pupae may be killed by a small wasp that develops within. Many insecticides labeled for residential use in landscapes that are available in garden centers may control elm leaf beetles and their larvae if the elm is small enough to be sprayed. In addition to standard chemicals, Heterorhabditis nematodes sprayed on the soil surface under elms at the time of elm leaf beetle pupation can help. These nematodes can be ordered on line. Another strategy is to apply a contact insecticide in at least a foot-wide band around the trunk of infested trees to kill larvae crawling down to pupate. However, migration of elm leaf beetles from untreated trees in the area will probably result in reinfestation. A white fungus, Sporotrichum globuliferum, attacks pupae and adults.

For commercial applications check recommendation in Southeastern US Pest Control Guide for Nursery Crops and Landscape Plantings.

Other Resources

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

Authors

Professor and Extension Specialist
Entomology & Plant Pathology
Professor Emeritus
Entomology & Plant Pathology

Publication date: Jan. 13, 2000

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