Among the many leafminers that affect ornamental and vegetable plants are:
American serpentine leafminer, Liriomyza trifolii
Beet leafminer, Pegomya betae
Birch leafminer, Fenusa pusilla
Boxwood leafminer, Monarthropalpus flavus
Columbine leafminer, Phytomyza aquilegivora and P. columbinae
Pea leafminer, Liriomyza huidobrensis
Spinach leafminer, Pegomya hyoscyami
Vegetable leafminer, Liriomyza sativae
Leafminers are the larval form of a fly in the order Diptera that cause damage to the edible foliage vegetable crops of spinach, beets, chard, other vegetables, and some ornamental trees, shrubs, and herbaceous plants. The feeding damage appears in the form of hollowed out whitish, serpentine tunneling patterns that will coalesce into larger blotchy areas in the mesophyll tissue between the upper and lower layers of the leaves. The tunneling larvae will also leave excrement behind, making vegetable leaves unfit for human consumption. Moderate damage will not affect beet root quality although severe leaf damage can result in poor root development.
Life Cycle
The adult flies of many vegetable leafminers appear in the spring from late April through mid-May after overwintering as pupae in the soil or in plant debris. The tiny, ¼”, hairy gray adult flies mate and the female will lay tiny white eggs either singly or in clusters on the undersides of the developing leaves of the host plant. The newly hatched legless larvae will burrow into the interior of the leaves to begin feeding. When the larvae are mature they will chew through the leaf surface, drop to the ground, and pupate. The life cycle of the leafminer is 30-40 days long so there can be 3-4 overlapping generations per year. Spinach leafminer adult, eggs, feeding damage, and larvae, below, right to left.
