Here are tips on how to identify and get rid of cabbage root maggots.
What are Cabbage Root Maggots?
Cabbage Root Maggots affect cabbage, cauliflower, broccoli, and Brussels sprouts. (This group of vegetables is also known as ‘cole crops’.) Different types of root maggots also occur that affect carrots, onions, and other veggie crops. Because cole crops are cool-season vegetables, Cabbage Root Maggots are much more prominent in Northern zones of the US. They are difficult to control, because they hatch and feed underneath the soil, so you may only know they are there when you notice stunted growth or wilting foliage.
How to Identify Cabbage Root Maggots
Cabbage Root Maggots are white, legless, and about 1/3 inch long. As with most maggots, they clump in groups and will feed voraciously on root systems of cole crops. The Cabbage fly is tiny, grey and fragile, and will emerge in early spring. After feeding for about 10 days, eggs are laid at the base of cole crop seedlings. Eggs are about 1/8 inch and oblong, and laid in rows, usually in moist or shaded areas (eggs are susceptible to heat damage, another reason they are mostly found in northern zones). Larvae hatch and tunnel through the soil to feed on the roots. You will notice wilting leaves, and sometimes a hint of blue cast or yellow in the foliage. Inevitably, the plant will die.
How to get rid of Cabbage Root Maggots
- Most red cabbage varieties have some resistance to Cabbage Root Maggots.
- Floating Row covers can be effective when set out at time of transplant. It is possible for overwintering pupae to emerge from beneath the cover. Make sure edges are sealed.
- If you see flies in the air, scout for eggs in the soil. Run your fingers through the top layers near the bases of your plants. Destroy any eggs found.
- Sticky traps in the garden are effective at trapping cabbage flies. They are available at most nurseries.
- Late planting can be a successful tactic in tricking pests.
- Check with your nursery about using nematodes as a biological control for root maggots. Another biological control are wasps, so leave them alone.
- Practice crop rotation.
- Till garden in the fall and spring to expose overwintering fly pupae.
- Check with your local Cooperative Extension  for your area's regulations on chemical control.
Cabbageworms are another common pest of the cabbage family. Click here to deter cabbageworms .