Cabbage Root Maggot

Diptera (Delia radicum)


The adults of cabbage root maggots are dark gray flies resembling small houseflies. They emerge in early spring and are able to travel up to 1.5 kilometers in search of host plants such as cabbage, broccoli, cauliflower, and brussel sprouts. Small white, bullet-shaped eggs are laid in the soil near the brassicas. The maggots are white, legless, and about 8 mm long and clump in groups feeding on the root systems of the hosts.

Life Cycle

The life cycle of cabbage root maggot comprises four stages: egg, larva (is called maggot), pupa, and adult. In the early spring, adult females emerge from the soil and lay about 50-200 small, white eggs in moist or shaded areas often near the main stem of brassicas plants.

Depending upon the temperature, eggs hatch three to seven days later, and maggots immediately start tunneling through the soil to feed on the roots for three to four weeks. After feeding, they pupate either in the root or in the soil and prepare for the transformation to cabbage root flies. There are one to four generations per year depending on the weather in different areas.


The larval stage of the cabbage root maggot can cause severe damage to all brassica crops. The young larvae by feeding on the root hairs and older larvae by creating extensive tunnels into the stem and root system damage the host plants.

This root feeding and tunneling interferes with proper nutrient uptake in the plant causing stunting or killing the plants. Even if the plant is not killed, the wounds that the maggots make on roots facilitate the entry of plant pathogens.



Place yellow containers of soapy water nearby the brassica crops. This will attract, trap, and drown the cabbage maggot flies.