How to Manage Pests

Pests in Gardens and Landscapes

Boxwood leafminer—Monarthropalpus flavus

Adults are tiny, delicate mosquitolike flies that lay eggs in new leaves during spring. Larvae are orange to greenish maggots that feed within leaves. Mines initially look like yellowish leaf blotches. Older larvae feed in groups. Leaf mines merge and leaves appear blistered or overall patchy yellow. Leaf margins may remain green.

Damage

Heavily infested plants grow slowly, drop leaves prematurely, have a sparse canopy, and terminals die back. Buxus harlandii, B. microphylla, and many cultivars of B. sempervirens are heavily damaged.

Solutions

Consider replacing susceptible species with resistant plants, including B. sempervirens 'Argenteo-variegata', B. sempervirens 'Pendula', or B. sempervirens 'Suffruticosa'. Rake and dispose of infested leaves in fall and winter; leafminers overwinter as pupae inside mined leaves.

Adult and leafminer pupa
Adult and leafminer pupa

Leaf blotches
Leaf blotches caused by leafminer feeding


Statewide IPM Program, Agriculture and Natural Resources, University of California
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