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.
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.
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.
and leafminer pupa
Leaf blotches caused by leafminer feeding