Pyrrhalta viburni
Pest description and damage Adults are brown and about 0.25 inch in length. Mature larvae are greenish-yellow and are about 0.375 inch long. The adults and the larvae both chew holes in the leaves, although the feeding damage is different. Adults chew oblong shot holes in the leaves, whereas the larvae skeletonize the leaves. The popular snowball bush, V. opulus, is one of the known hosts of this beetle, although it may infest other Viburnum species grown in the PNW.
Biology and life history Viburnum leaf beetle are a European insect that is currently restricted to northwest Washington and British Columbia in Canada. The insect overwinters as eggs. The female beetle chews square holes in the twigs and deposits the eggs, then covers them with a black cap of wood chips and excrement. The eggs hatch in the spring and the larvae feed on the young expanding leaves. Adults appear in mid-summer and seen until frost.
Management-cultural control
Individual infested twigs with overwintering eggs clusters are pruned out in the dormant season. Watch for feeding damage in the early spring and pick off or hose off the larvae.
Management-chemical control
See Table 2 in: