Viburnum Leaf Beetle

Pest Alert: Viburnum leaf beetle detected in new Massachusetts counties (August 1, 2008)

(Click on an image below to see the captioned full-size version)
Figure 1		Figure 2		Figure 3		Figure 4		Figure 5		Figure 6

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. (Figure 1)
	Mature larvae are 10-11mm (about ½ inch) long, yellowish brown, and have spots. (Figure 2)
	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. (Figure 3)
	Egg “caps” are 1-2mm in diameter, brownish-black in color, and arranged in straight rows on the under surface of terminal twigs. (Figure 4)

Description of damage:
	Larvae feed on the areas between leaf veins, leaving "skeletonized" leaves. Larval damage is seen from late April through the summer. (Figure 5)
	Adults chew irregular circular to elliptical holes in the leaves. Adult damage can be seen from late June until leaf drop in fall. (Figure 6)

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 (Neogalerucella) beetle, which is used as a biological control for purple loosestrife (Lythrum salicaria), 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

Cornell University, Department of Horticulture, Viburnum Leaf Beetle home page
http://www.hort.cornell.edu/vlb/index.html

Cornell University Fact Sheet
http://www.entomology.cornell.edu/Extension/Woodys/VLBfactsheet2000.pdf

Viburnum Leaf Beetle Pyrrhalta viburni (Paykull) in the Nursery and Landscape
Ministry of Agriculture and Food, Ontario, Canada
http://www.omafra.gov.on.ca/english/crops/facts/vlb.htm

Viburnum Leaf Beetle: Pennsylvania State University Entomological Notes
http://www.ento.psu.edu/extension/factsheets/viburnum_leaf.htm

Viburnum Leaf Beetle: University of Guelph Pest Diagnositic Clinic
http://www.uoguelph.ca/pdc/Factsheets/Insect/viburnum.htm

last reviewed July 31, 2008