Control of the Viburnum Leaf Beetle

Pesticides

• Unfortunately, the insecticides that control viburnum leaf beetles are also harmful to the beneficial insects that control leaf beetle infestations. The most effective management is to apply or spray insecticides upon the larva as soon after they emerge as possible. Application of insecticides on eggs and adults is less effective. The larvae feed on the underside of new and emerging leaves. Inspect the viburnum prior to spraying to determine the exact location of the larvae and apply accordingly. An organic insecticidal soap that contains spinosad, a pesticide derived from the saccharopolyspora fungus, is effective against the larvae.

Horticultural Oil

• Horticultural oil, which is highly refined petroleum oil mixed with water, sprayed on eggs of the viburnum leaf beetle reduces hatching. A high percentage of oil is most effective when applied prior to leaves emerging, generally in early May. While this high percentage of oil is effective against the leaf beetle eggs hatching, is also detrimental toward foliage.

Prevention

• To prevent future infestations, prune and destroy infested branches during the winter and monitor egg activity at the first frost in the fall. Any branches that show egg scars also need to be destroyed through the months of October through early May. When disturbed, adult leaf beetles will drop to the ground and can be destroyed with soapy water. Gently tap leaves to remove the beetles, and repeat as necessary to ensure all adult beetles are removed. Larvae can be trapped by applying a sticky barrier, commercially available as an insect barrier, around the base of the plant.

Resistant Viburnum

• Consider planting cultivars or species of viburnum that have a resistance to the leaf beetle. Such species include the doublefile viburnum, Burkwood viburnum, Koreanspice viburnum, leatherleaf viburnum and the Judd viburnum. Although these species have shown to possess some resistance to the viburnum leaf beetle, management control should still be practiced.