Elm Leaf Beetle

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Xanthogaleruca luteola

Description

Adults of elm leaf beetles are about 6 mm long, greenish-yellow with black strips along the margin and centre of the wing covers. The adult beetle and larvae feed only on elm trees and are the most serious elm defoliator.

Life Cycle

The elm leaf beetle has four life stages: egg, larva, pupa, and adult. The adult beetles commonly overwinter in protected locations such as in bark crevices, woodpiles, or buildings. In spring, when the elm trees leaf out, the adult beetle emerges, flies to elm foliage, and chews the leaves. The females lay eggs in double rows on the underside of leaves total deposits of 400 to 800 eggs. Larvae emerge in a couple of weeks and chew on the elm leaves. The full-grown larvae crawl down the tree trunk to pupate in the soil. After about a week, the adults emerge, fly on the elm tree, and feed on the foliage and the life cycle continues. The elm beetles have one to four generations per year according to the climate and weather conditions.

Damage

The elm leaf beetle feeds only on elm and the larvae are the most devastating stage of the insect as they feed the underside of the leaves and skeletonize them. Skeletonization of the leaves prevents the leaf from photosynthesizing and causes them to turn brown to whitish and drop prematurely. Adult beetles chew the leaf and create small round holes. When they are abundant can completely defoliate large elm trees resulting in significantly lower scenic beauty and recreational value. Repeated attacks may extensively weaken elms, and causes trees to decline.

Control

  • V9 Tree Belt

Advice

  • Practice good cultural techniques by providing appropriate irrigation, and nutritional or injury-induced stress to maintain trees’ health and vigor.
  • Adult elm leaf beetles overwinter in woodpiles, leaves, or other debris near elm trees. Eliminate the areas from these potential overwintering hideaways.

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