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Insect and Mite Pests of Boxwood

ID

ENTO-42NP (ENTO-314NP)

Authors as Published

Eric Day, Manager, Insect Identification Laboratory, Department of Entomology, Virginia Tech

Three pests, the boxwood leafminer, mite and psyllid commonly attack American and English boxwood in Virginia and cause spotting, yellowing, and puckering of leaves.

Guide to Boxwood Pests and Their Control Based on Damage

Boxwood Mite (A): Leaves of infested plants appear to be pinpricked or scratched with tiny white or yellow marks. The boxwood mite is one of the spider mites and is difficult to find even under a dissecting microscope. Eggshells and cast skins can be important clues but they are not as noticeable as they are with other spider mite species. Boxwood mites can be controlled with dormant oil applications in late winter or insecticidal soap sprays in May.

Boxwood Leafminer (B). Infested leaves appear blistered on the underside and are often discolored. The adult boxwood leafminer is a small, delicate fly. Damage when the larvae feed between the upper and lower layers of leaves. Two to six larvae typically occur in a single leaf. With a little practice, they are easily found by breaking open a blistered leaf with your thumbnail. Boxwood leafminers can be controlled with a soil drench of a systemic insecticide such as imidacloprid in April.

Boxwood Psyllid (C.): Their feeding on tender new growth causes leaves to cup and stunts the growth of shoots. Although the leaves are cupped in the spring, the damaged leaves remain on the plant for several years. Nymphs cover themselves with white, cotton-like secretions and can be found in April and May. Adults are rarely seen. Contact insecticides or systemic insecticides applied just after bud break provide good control.

Life History

Boxwood Mite, Acari: Tetranychidae, Eurytetranychus buxi (Garmon) overwinter as eggs on the undersides of leaves. Eggs hatch in April or May. It is one of the spider mites and is difficult to find even under a dissecting microscope. Eggshells and cast skins can be important clues but they are not as apparent as they are with other spider mite species.

Boxwood Leafminer, Diptera: Cecidomyiidae, Monarthropalpus buxi, Larvae overwinter within their mines. Adult flies are evident around boxwoods in late April and early May. It is a small, delicate fly as an adult but it’s the larval stage that feed between the upper and lower layers of leaves and causes the damage. Two to six larvae typically occur in a single leaf. With a little practice, they are easily found by breaking open a blistered leaf with your thumbnail.

Boxwood Psyllid, Homoptera: Psyllidae, Psylla buxi adults are active during July and early August, but they are rarely seen. Eggs are laid between bud scales and nymphs emerge from them in mid-to-late April. Nymphs soon cover themselves with white, cotton-like secretions. Member of a family of insects closely related to aphids. Adults are rarely seen. Nymphs cover themselves with white, cotton-like secretions.

CHEMICAL CONTROL Consult the latest version of the Virginia Pest Management Guide 456-018 or 456-017 for currently labeled insecticides and miticides as registrations and precautions can change. Follow all instructions on the pesticide label and wear protective clothing. 


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Publication Date

April 3, 2019

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