The Pesky Viburnum Leaf Beetle

CMBG At Home, Gardening, Horticulture, Outdoors

A very pesky pest! Viburnum leaf beetle (Pyrrhalta viburni) is an invasive beetle that defoliates viburnums spring through summer. Sound familiar? Read on for some tips for dealing with this insect. 

Viburnum leaf beetles are small brown/black beetles, considered an invasive pest insect in Maine and native to most of Europe and parts of Asia, that emerge in the spring as larvae from eggs laid on the underside of viburnum twigs. Larvae go through three instars, or stages, before they become adults in late July. In all stages of their life cycle they feed on viburnum leaves. Because they crawl into the ground and stop feeding for a while when they pupate into beetles, then reemerge to feed once more, it can seem like there are multiple generations in one year. As adults, they mate and start laying eggs on the underside of the twigs up until the first frost when the adults die off. In each egg-laying site there are about eight eggs. These eggs are covered with a cap constructed from chewed bark that the females deposit over the eggs to protect them.

Eggs on a branch
Viburnum leaf beetle larvae

But here’s the question—how do you get rid of them? The best control is through pruning since the beetles lay their eggs on the underside of the recent year’s growth. In other words, the eggs are deposited on small twigs that will hardly be noticed if pruned off. The best time to prune is October through the end of April, before larvae start emerging. Once pruned off, collect the twigs and branches and destroy them. They make great kindling for those early spring fires! Once you have identified that your viburnums have the pesky beetle, it’s best to keep checking them every winter for more eggs. The population after the first year will be greatly reduced, and a small amount of pruning here and there should keep them in check.

Viburnum dentatum, new leaf
Viburnum cassinoides


Here’s a list of susceptible viburnums:

V. dentatum, arrowwood viburnum

V. nudum, smooth witherod

V. opulus, European cranberrybush

V. opulus ssp. trilobum, American cranberrybush

And resistant viburnums:

V. x bodnantense, Bodnant viburnum

V. carlesii, Koreanspice viburnum

V. rhytidophyllum, leatherleaf viburnum

V. setigerum, tea viburnum

Source and more information: http://www.hort.cornell.edu/vlb/suscept.html

CMBG Horticulturist Kelsie Birney graduated from the University of Maryland with a certificate in general ornamental horticulture and takes charge of the Burpee Kitchen Garden and the terrace loop. With another member of the horticulture team, she’s been working on a program on beneficial insects. She also teaches classes throughout the season