New Viburnum Pest Headed South

Contact: Mary Kay Malinoski, Maryland Cooperative Extension | mkmal@umd.edu | 800-342-2507

Paul Weston, Cornell University, Bugwood.org

ANNAPOLIS, MD (April 17 2006) – The viburnum leaf beetle, Pyrrhalta viburni, is a recent unintentionally introduced pest of viburnum in North America. It was first found in upstate New York in 1996. This pest has been on the move ever since munching its way through native and landscape viburnums from upstate New York to northern Pennsylvania. It has not reached Maryland yet, but we need to be on the look out for it. This serious pest of native and landscape virburnums has earned the designation of “Invader of the Month” for April by the Maryland Invasive Species Council.

Larvae and adults feed on the foliage and can severely damage and eventually kill some species of viburnum. Larvae hatch in early May initially feeding together and skeletonizing the underside of leaves. As they grow, they consume the foliage. High populations may completely defoliate the shrub. Mature larvae are 10-11 mm long and yellowish-brown with black spots. They pupate in the soil in early to mid-June. Adult beetles are brown and about 4.5-6.5 mm long. They emerge in July and are present through September. Adult feeding appears as oblong holes in the leaves. Females lay eggs in cavities on twigs in late summer and fall. This beetle is spreading its range and is currently found in New York, Maine, northern Pennsylvania, Vermont, parts of Ohio, Canadian Maritime provinces, Ontario, and British Columbia.

Management Strategies
Look for egg laying sites on the twigs. Prune these twigs and dispose of them. The egg masses are easiest to find after viburnums have dropped their leaves. To control young larvae, monitor for skeletonized new leaves and use a registered insecticide, if necessary. Some species of viburnum appear to have resistance to this pest. Plant resistant varieties of viburnum such as dawn viburnum, V. bodnantense, Koreanspice viburnum, V. carlesii, David viburnum, V. davidii, Judd viburnum, V. x juddii, doublefile viburnum, V. plicatum, doublefile viburnum, V. plicatum var.tomentosum, leatherleaf viburnum, V. rhytidophyllum, tea viburnum, V. setigerum, and Siebold viburnum, V. sieboldii. Encourage beneficial insects in the landscape. Several native predators such as the spined soldier bug, and lady beetles feed on viburnum leaf beetles. Research is underway to explore more biological control options.

Keep an eye out for feeding damage on viburnum. If you suspect viburnum leaf beetle, contact Dick Bean, entomologist, at the Maryland Department of Agriculture at 410-841-5920. You may also contact the University of Maryland Home and Garden Information Center at 1-800-342-2507 or hgic.umd.edu. For more information on the viburnum leaf beetle visit Cornell University’s Citizen Science web site at http://www.hort.cornell.edu/vlb/.

VLB larvae. Photo: Paul Weston, Cornell University, Bugwood.org
VLB egg masses. Photo: Bruce Watt, University of Maine, Bugwood.org
VLB larval damage. Paul Weston, Cornell University, Bugwood.org
VLB adult damage. Paul Weston, Cornell University, Bugwood.org

For more information about other Invasive Species of Concern, visit the Maryland Invasive Species Council.