Leafminers attack many different flower hosts, including
aster, begonia, dahlia, impatiens, lily, marigold, petunia,
and verbena. Adult Liriomyza are
small, active, black and yellow flies. The most important
species are the serpentine leafminer (Liriomyza trifolii)
and the pea leafminer (L. huidobrensisa). Larvae
are yellow cylindrical maggots.
Adult female leafminers puncture leaves and sometimes petals to feed on exuding sap. These punctures eventually turn white, giving foliage a stippled or speckled appearance. Larvae make a winding tunnel (mine) or sometimes a blotch between the lower and upper leaf surface. The mine becomes longer and wider as the larva grows. Mining usually has little impact on plant growth and rarely kills plants. Unusually heavy damage can slow plant growth and may cause infested leaves to drop.
Provide proper care, especially irrigation
to keep plants vigorous. Clip off and remove older infested
leaves. Plant resistant species or varieties. Leafminers
are often kept under good control by natural parasites.
Insecticides are not very effective for leafminer control.
Adult serpentine leafminer
Foliage damaged by leafminer larvae