Defoliators
> Viburnum Leaf Beetle
Pest: Viburnum Leaf Beetle (Pyrrhalta virburni)
Order: Coleoptera
Family: Chrysomelidae
The Viburnum Leaf Beetle has not yet been officially identified
in Massachusetts as of the summer of 2000. However, it has been
in New York State, Maine, and Quebec Canada for a number of years
now. Both the immature and adult stages are serious defoliators
of many viburnums. It is expected that this pest will be found some
time soon in Massachusetts and other New England states.
Host Plants:
This native of Europe feeds exclusively on many different species
of viburnum, which include: Viburnum opulus (and cultivars),
V. dentatum, and V. rafinesquianum.
Adults have also been found feeding and laying eggs on V. lentago,
V. acerifolium, and V. trilobu.
Life Cycle:
This pest over-winters as an egg on the twigs of the host plant.
Eggs hatch in May of the following year and the young larvae begin
feeding on the host plant foliage. Larvae are usually found feeding
together in groups. Pupation occurs 8-10 weeks later and the first
adults begin to appear around the middle of July. Adults are active
up until the first frost. Mating occurs, starting in July, and the
female will chew small holes in the twigs where she lays her eggs.
She then proceeds to cover these individual eggs with excrement
giving the bark of these twigs a roughened appearance. Each female
produces up to 500 eggs. (Source: Insects That Feed on Trees
and Shrubs. Johnson and Lyons).
Injury and Appearance:
Both the larvae (immatures) and the adults feed voraciously on the
foliage of the host plants. Heavily attacked plants will have every
leaf skeletonized by this pest. It is the only pest that causes
such injury to viburnums.
Adults are small and brown and somewhat difficult to see. The
immatures are dark in color and can be found feeding in groups on
the host foliage.
Management:
Homeowners need to be aware of the signs of this beetle’s injury
along with knowing what the different life stages look like. One
should also monitor for the eggs on the stems of viburnums. When
found, this pest should be treated to limit its injury and spread.
Physical removal of this pest from the host plant is difficult to
obtain especially when many plants are involved. Therefore, pesticide
treatments may be necessary to manage this pest, once found.
Images:
Defoliators
index:
Asiatic Garden Beetle 
Bagworm
Cankerworms
Eastern Tent Caterpillar
Fall Webworm
Forest Tent Caterpillar
Gypsy Moth
Japanese Beetle
Larch Casebearer
Lily
Leaf Beetle
Mimosa Webworm
Viburnum Leaf Beetle
Winter
Moth - ID & Management
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Winter
Moth Project - Biological Control in MA
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