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How to Identify and Get Rid of Cabbage Root Maggots

The larva of the cabbage root fly, or the cabbage root maggot, can be a serious pest, so learn how to get rid of it here.

Photo Credit
Ian Bedford/GrowVeg.com

Learn How to Prevent Cabbage Root Maggots

Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Calling all gardeners!  Are your cabbages wilting and your Brussels sprouts looking sickly? Cabbage root maggots might be the culprit.  This guide equips you with everything you need to know to identify, control, and prevent 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 the 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.

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Identification

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. It resembles a small housefly. 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). They can often be seen near the main stem in the soil.
  • Larvae hatch and tunnel through the soil to feed on the roots. After feeding, they become cabbage root fly pupae and prepare for the transformation to become cabbage root flies.
cabbage root maggots in the pupal stage
Cabbage root maggots in the pupal stage signify that you will soon have cabbage root flies in your garden.
Photo Credit: Ian Bedford/GrowVeg.com. 

Cabbage Root Maggot Damage

You will notice wilting leaves and sometimes a hint of blue cast or yellow in the foliage. As the larvae tunnel through the roots, the plants will wilt and shrivel. If you pull up the damaged plants, you will see the tiny maggots on the roots. Inevitably, the plant will die. Cabbage root maggots cause the most damage in late summer.

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Control and Prevention

How to Get Rid of Cabbage Root Maggots

  • 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.
  • You can try installing ‘cabbage collars’ at the base of the stem. These can be made from cardboard and will simply be a skirt around the base of the plant. It protects the plants from egg-laying.
  • Sticky traps in the garden are effective at trapping cabbage flies. They are available at most nurseries.
  • Check with your nursery about using nematodes as a biological control for root maggots. Another biological control are wasps, so leave them alone.
  • Carefully dig up your plants and swish their roots in cold water to remove the maggots, then replant them. Either allow the maggots to drown in the water or feed them to your chickens for a tasty snack.
  • Check with your local Cooperative Extension for your area’s regulations on chemical control.
  • Old folk advice from The 1963 Old Farmer’s Almanac says that the smell of tar in tar paper was effective against cabbage root maggots.

Prevent 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.
  • Late planting can be a successful tactic in tricking pests.
  • Practice crop rotation.
  • Till garden in the fall and spring to expose overwintering fly pupae.
  • If you’d like to keep cabbage root maggots away from more valuable plants, try planting radish as a trap. Many maggots will be attracted to the radish, and then you can destroy it.

Cabbage worms are another common pest of the cabbage family. Click here to deter imported cabbage worms.

Garden Pests
About The Author
Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann is the Executive Digital Editor of Almanac.com, the website companion of The Old Farmer's Almanac. She covers gardening, plants, pest control, soil composition, seasonal and moon c...
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Comments

<span>Katherine</span> Wed, 10/30/2024 - 16:15
Implanted radishes in my raised bed garden and the leaves looked like something w
<span>Katherine</span> Wed, 10/30/2024 - 16:16
Katherine again looked like something was eating the leaves
<a title="View user profile." href="/author/joe-bills">Joe Bills</a> Mon, 11/04/2024 - 10:04

It sounds you might be dealing with a different sort of pest. Perhaps a cabbage looper. The following page from the Maine Dept. of Agriculture offers some additional info about identifying cabbage pests and figuring out what to do about them: https://www.maine.gov/dacf/php/gotpests/bugs/cabbage-worms.htm

 <span>Arlene F Whitney</span> Sun, 10/16/2016 - 18:15
It looks like I have maggots on the roots of my rose bushes howling them out and killing them so they can anybody help me
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 10/17/2016 - 12:47


It is difficult to say what kind of larvae are boring into your rose roots. To get rid of them: Prune the rose canes to be 5 to 6 inches high, then gently dig up the shrub, hose off the roots (over a barrel or bucket full of warm soapy water) until all of the larvae are gone from the roots, remove the affected soil and replace it with new soil and compost, and replant. If the rose is too badly damaged, consider replanting with a new rose. Be sure the larvae are dead before discarding them. If done in the fall, your rose should bounce right back in the spring.

 

 <span>Richard, Bicester</span> Fri, 06/05/2015 - 12:58
I pulled my cabbage and sprouts that has CRF, rinsed the soil of them, and the maggots. Planted them back with some ash from the fire/BBQ and they recovered. Then thr bloody butterflies got them!!