(Monarthropalpus buxi)
The boxwood leafminer is one of the most serious pests of boxwood. The larvae spend the winter in the leaf. When the weather warms in spring, they feed on the tissue between the leaf surfaces. In late April or May a tiny (1/10 inch), gnatlike, orange fly emerges from the pupal case inside the leaf. The emerging flies swarm around the plant in early morning, mating and laying eggs in the leaves. New blisters develop in midsummer from feeding by this next generation of larvae. When the weather turns cold, the larvae become inactive until the following spring.
Leafminer control is most effective when insecticides are applied just before eggs are laid in late spring. Spray with an insecticide containing acephate or lindane in late April or early May. If eggs are laid before a control is applied, an insecticide containing dimethoate applied in late June may kill young miners.
Plant Care for Buxus