Quick Facts

  • Discovered in New York state in July 1996
  • Larvae are quite small and darkly colored when they first emerge
  • Adult beetles are 4.5-6.5 mm in length and brown in color
  • Beetle’s life cycle (from egg hatch to adult) takes about 8-10 weeks

Species Facts:

The Viburnum Leaf Beetle, Pyrrhalta viburni , can cause severe defoliation of ornamental viburnums, branch dieback and eventually can kill the plants. This pest has a high entry and establishment potential for the Southeast. In the early spring, one should closely examine the small twigs from the previous season. Also, a person should look for the overwintering egg sites (holes and scars). As the temperature increases, these holes appear to swell and the caps of the holes fall off. Once leaves have begun to expand, one should examine both the surface and the underside for feeding larvae and also watch for skeletonized leaves. Both the adult and the larva feed on the leaves between the midrib and larger veins. This gives the leaves a lace-like or skeleton appearance. Plants which have been defoliated for 2 or 3 consecutive years may be killed.

Viburnum leaf beetles overwinter as eggs. Eggs hatch in May and the larvae begin feeding on the developing leaves. First feeding injury appears as small pin pricks or holes. By June the skeletonizing has become quite apparent. In June, larvae drop or migrate to the ground to pupate in the soil. Adult beetles emerge in late July. When disturbed, they will fly away or drop to the ground.

Females lay eggs from late summer to the first frost. A hole is chewed in the small twigs. Several eggs are laid in each hole, which is then covered with a mixture of chewed wood and excrement. Egg laying holes can be found in a straight line on the underside of the current season's growth. A single female may lay up to a total of 500 eggs per season.

Portions of this article courtesy of: Ontario: Ministry of Agriculture, Food, and Rural Affairs
Image of skeletonized leaves left behind by Viburnum Leaf Beetles (Photo from: www.bugwood.com Credit to: Paul Weston)