4.6 Leaf beetles - Canadian Nursery Landscape Association

4.6 Leaf beetles
Taxonomy and appearance
Class: Insecta
Order: Coleoptera
Family: Various
Both adult and larvae of leaf-eating beetles feed on foliage.
skeletonization or leaf mining.
They can cause significant defoliation,
Viburnum leaf beetle (Pyrrhalta virburni) is an introduced pest to North America. Adults are brown and 4.5 –
6.5mm long. Newly hatched larvae are off-white to greenish-yellow and eventually become yellowish-brown
with black spots. Eggs are laid in stems and the oviposition sites appear as rows of small 1`-2mm diameter
spots.
Elm leaf beetle (Pyrrhalta luteola) is also an introduced species. The adult beetles are approximately 6.5
mm long and are yellow to olive-green, with two black stripes on either side and three black spots on the
thorax. The larvae are dull yellow with two rows of black spots on their back. Yellow-orange eggs are laid in
clusters on the undersides of leaves.
Susceptible hosts
Table 4.6.1. Leaf beetles and susceptible hosts
Beetle
Susceptible Hosts
Viburnum leaf
beetle
Various varieties and species of Viburnum (Viburnum opulus is highly susceptible)
Elm leaf beetle
All species of elm are susceptible, especially chinese, English and siberian elms (Ulmus
parvifolia, U. procera, and U. pumila respectively)
Damage symptoms
Viburnum leaf beetle larvae and adults are foliage feeders with the larvae eating along the leaf veins leaving
a lace-like skeletonized leaf and the adults chewing oblong shot holes. Successive feeding by larvae followed
by adults do allow bushes time to re-vegetate between beetle stages. Two or three consecutive years of
defoliation can cause significant dieback of the canopy and kill a bush.
Elm leaf beetle larvae feed between veins on the lower surface skeletonizing the leaves. Adults also
skeletonize leaves and will feed on buds and expanding leaves early in the season. Severely damaged
leaves appear brown and often prematurely drop. Several years of severe defoliation can lead to dieback or
death of the tree.
Figure 4.6.1. Viburnum leaf beetle larvae
Figure 4.6.2. Viburnum leaf beetle feeding
damage on Viburnum opulus nanum
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Figure 4.6.3. Viburnum leaf beetle adult
Figure 4.6.4. Viburnum leaf beetle oviposition
scares on branch
Resources
Ontario Ministry of Agriculture and Rural Affairs. Nursery and Landscape Plant Production and IPM. Publication 383.
Canadian Nursery Landscape Association
University of Guelph fact sheet
Photo Credits
1 – 4. DessIsaa Horicultural Consultants Inc.
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