Protect spinach, swiss chard, and other greens from leafminers.
Leafminers in vegetables are small flies. Two commonly encountered species are spinach (Pegomya hyoscyami) and vegetable (Liromyza sativae) leafminers.
- Spinach leafminer flies are 1/4 inch long and gray or brown with black bristles. The larvae are whitish and carrot-shaped and do not have legs or an obvious head.
- Adult vegetable leafminers are 1/15 inch long and yellow and black. The larvae are yellowish-green with a cylindrical body. They also do not have legs or an obvious head.
Damage Caused by Leafminers
Larvae will tunnel in leaves of plants which causes them to be undetectable. One larva may feed on more than one leaf. Spinach leafminers create irregular round-shaped mines (blotch), while vegetable leafminers have winding snake-like mines.
- Spinach leafminers will feed on vegetables such as spinach, Swiss chard, tomato, cucumber, and celery.
- Vegetable leafminers feed on vegetables such as bean, pea, eggplant, pepper, tomato, potato, cucurbits, beet, onion, and lettuce.
Life Cycle of Leafminers
- Spinach leaf miners lay eggs on the underside of the leaves side by side singly or in batches of up to five. Several generations can occur each year.
- Leafminers will overwinter as pupae. In spring, adults appear from mid-April to May. Adult flies will lay eggs on the undersides of leaves or inside of them. The first generation can cause serious damage compared to the other generations that appear later. After feeding for about two weeks, the larvae drop from the leaves onto the ground and pupate.
Management of Leafminers
- Place row covers over plants to prevent adults from laying eggs.
- Remove host weeds (chickweed, lambsquarter, nightshade).
- Deep spring plowing or rototilling to bury overwintering pupae.
- Remove attacked leaves, and apply insecticides on eggs before they hatch into larvae.
Contact your county Extension office for current pesticide controls.