Viburnum Leaf Beetle

Pest Alert: Viburnum Leaf Beetle detected in new Massachusetts counties

Scientific Name: Pyrrhalta Viburni
Common Name: Viburnum Leaf Beetle

Known Hosts:
The Viburnum Leaf Beetle only feeds on Viburnum species.

• Species that are known to be the most susceptible to Viburnum Leaf Beetle damage include: the V. dentatum complex (arrowwood viburnums), V. opulus (European cranberry bush), V. opulus var. americana (American cranberry bush, and V. rafinesquianum (Rafinesque viburnum).
• Species also known to be susceptible include: V. lantana (wayfaringtree viburnum), V. lentago (nannyberry), V. prunifolium (blackhaw viburnum), and V. sargentii (Sargent viburnum).

Current Distribution:
As of July 2008, the Viburnum Leaf Beetle has been confirmed in the following Massachusetts counties: Berkshire, Bristol, Franklin, Middlesex. It has previously been found in the states of Connecticut, Maine, New Hampshire, Vermont, New York, Ohio and Pennsylvania.

Key ID Features (Adults, Larvae, Eggs):

• Larvae hatch in late April and feed until mid-June, then pupate.
• Immature larvae are about 1mm long, greenish-yellow to off-white, and lack spots. They are typically found on the underside of leaves and are very difficult to see.
• Mature larvae are 10-11mm (about ½ inch) long, yellowish brown, and have spots.
• Adults are brown, 4.5-6.5mm (about ¼ inch) in length, and can also be difficult to see. Adults emerge in early July and feed until leaf drop.
• Egg "caps" are 1-2mm in diameter, brownish-black in color, and arranged in straight rows on the under surface of terminal twigs.

Description of damage:

• Larvae feed on the areas between leaf veins, leaving "skeletonized" leaves. Larval damage is seen from late April through the summer.
• Adults chew irregular circular to elliptical holes in the leaves. Adult damage can be seen from late June until leaf drop in fall.

Suggested Control Options:

• Twigs with egg masses can be pruned and destroyed while beetles are inactive (October-April).
• Horticultural oil sprays applied to egg laying sites may reduce egg hatch by 75-80% (before leaves emerge in spring).
• Larvae can be treated with registered pesticides, including Conserve, Orthene, Sevin, or Lorsban. (April-May, when eggs hatch). Adults can be treated with Decathlon or other registered pesticides (late June-October). Note: Pesticides not labeled for household use should only be applied by a licensed professional.
• If you are a seller or grower of Viburnum, be sure to isolate any infested plants.

Similar species or symptoms:
No similar species are found feeding on viburnum. The related Galerucella beetle, which is used as a biological control for purple loosestrife, looks similar but is slightly smaller and does not attack Viburnum shrubs.

Fact sheets and references:
Printable pest alert and fact sheet for sellers and growers of Viburnum, from the Massachusetts Department of Agricultural Resources
http://www.massnrc.org/pests/linkeddocuments/ViburnumLeafBeetlePestAlertFactSheet.pdf

UMass Extension Viburnum Leaf Beetle fact sheet
http://www.umassgreeninfo.org/fact_sheets/defoliators/viburnum_leaf_beetle.html

The content above was solely provided from the Massachusetts Introduced Pests Outreach Project which is a collaboration between the Massachusetts Dept. of Agricultural Resources and the UMass Extension Agriculture and Landscape Program. This information was made possible, in part, by a Cooperative Agreement from the United States Department of Agriculture's Animal and Plant Health Inspection Service (APHIS). It may not necessarily express APHIS' or Mayer Tree Service's views.