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Cabbage Maggot

© Carla Goodloe

They range anywhere in North America where cole crops are grown.

Adults are ash-gray flies about a quarter inch long with black stripes on the thorax and black bristles all over the body. resembles a small housefly. White eggs are laid at the base of plants at the soil line. Larvae are white, about a quarter inch long, blunt at the rear, and pointed on the front. The adults lay the eggs, the larvae hatch, and then the larvae tunnel into the root crops causing wilt and bacterial or fungal diseases. Larvae feed for three or four weeks before pupating, then hibernate in the soil as pupa. Adults emerge and two or three broods per year make their rounds. The pest is dormant when temperatures are above 70 degrees.

Meals include cabbage, cauliflower, broccoli, radish, brussel sprouts, and turnips. The damage is extensive and the vegetables non-edible.

Controls include rove beetles which prey on the maggot eggs and young larvae. Rove larvae parasitize the pupa stage of the maggot. Keep lots of organic soil in your garden to attract the rove beetle. A tiny wasp called Trybliographa rapae will lay its eggs in the maggot larva if the larva are close enough to the soil surface.

Other controls include covering healthy plants with row covers until they get established. Put 6 inch collars around the base of the plants to prevent adults from laying eggs near the plant stems. Remove wild mustard weeds because the flies love them.