Viburnum Leaf Beetles
Viburnums are a wonderful group of deciduous shrubs for the landscape. They have stunning fall colour, lovely white or pink flowers in spring, followed by red or purple/black berries in fall that are irresistible to birds. Unfortunately, this gem of a plant is also irresistible to a certain insect as well. The Viburnum Leaf Beetle eats the leaves of this prized shrub leaving it skeletonized and barren in a matter of days. Damage occurs in June by the larva of this beetle. After the Viburnum Leaf Beetle larva has finished feeding, it completes its metamorphosis, becoming an adult. In July, the females bore rows of holes in the twigs of the viburnum to lay eggs. She then covers them with excrement which keeps them safe throughout the long winter. The eggs hatch in May and another generation of the larva begin their frenzy again.
To help control viburnum leaf beetle populations, check for eggs in late fall and early spring. Prune and destroy any infected branches. Apply Dormant Oil Spray in early spring just before the buds break, as this will smother some of the eggs before they get a chance to hatch. Beneficial insects such as Lady Bugs and Lacewings will feed off of the larva of the viburnum leaf beetle. Insecticidal soap will work on the larva, but you need to coat the insect in order to kill, so spray carefully! Be warned that insecticidal soap also kills beneficial bugs so use it as a last resource.
Viburnum leaf beetle attacks can kill the plant if they defoliate it 3 years in a row. On a brighter note, these pests have preferred types of Viburnums that they like the best. When considering viburnums for your landscape (which you should despite this issue), choose one of the least susceptible kinds so you can enjoy and not be disappointed!
Viburnum opulus, European highbush cranberry
V. lantana, wayfaring tree viburnum, V. rafinesquianum, rafinesque viburnum
V. dentatum, arrowwood viburnum, V. trilobum, American highbush cranberry viburnum
INJURED FROM ADULTS UNDER LABORATORY CONDITIONS
V. acerifolium, maple leaf viburnum, V. lentago, nannyberry viburnum