Cabbage Worms in Your Garden
How to Control Cabbage Worms
As you can see from the picture above, cabbage worms are troublesome little caterpillars, velvety green and a little over an inch in length. They are especially fond of cabbage and cauliflower, but will eat other members of the same plant family also.
About Cabbage Worms:
Cabbage worms are the immature form of the Cabbage Worm Butterfly. You've probably seen the butterflies in the garden, without realizing it.
The butterfly is usually around 2" across in wingspan and white in color. The female butterflies have a tell-tale marking of two black spots on the top set of wings. The males have only one set of black spots. The butterflies are active during the day, feeding on nectar.
While the butterflies themselves aren't harmful, they lay eggs that become the destructive cabbage worms. (They can produce between 3-6 generations in one gardening season, depending upon the length of the season.)
The cabbage worms can often be seen in the garden as soon as the Spring temperatures start to warm. And, will continue to be a problem in the garden up until Autumn's hard frost.
Cabbage worms start eating on the outer leaves of the cabbage (where they're still visible), working their way in to the center of the cabbage head, leaving a trail of green excrement (as you can see in the photo above).
Note: If you're going to pick them by hand, you need to catch them before they burrow into the cabbage head.
Prevention to Control Cabbage Worms:
Using these preventative gardening practices can help minimize the risk of cabbage worm infestation in your garden:
1. Rotate your crops in your garden. Do not plant any cabbage family crops in the same location as was previously used by a cabbage family crop.
2. Do not leave cabbage leaves or stalks after the harvest laying around in your garden. This just provides a breeding ground for cabbage worms. Compost them, burn them, or otherwise remove them from the garden.
3. Make sure the soil pH is suitable for cabbage before planting your crop, and that the crop is adequately fertilized. (See fertilizing requirements for growing cabbage.) Healthy plants are less prone to insect problems.
How to Treat your Garden to Eliminate Cabbage Worms:
Dust the affected plants immediately when you notice caterpillars feeding on the plants.
(Note: This isn't our preferred method, as pesticides leave a residue that you end up eating, and that stays in the soil also. We encourage you to investigate the benefits of organic insect control.) If you do dust with a pesticide, be sure to at least follow the manufacturer's recommendations for a waiting period before harvesting, if not longer.
Organic Options for Controlling Cabbage Worms:
- Create habitats to encourage nature's predators of the various stages of the cabbage worm's life.
Natural enemies of cabbage worms are wasp-like parasites, paper wasps, four-winged flies, sparrows, and wrens. Ambush bugs (fond of goldenrod for a habitat) will capture and eat the cabbage worm butterflies.
- Pick the cabbage worms by hand, and place in a bucket of soapy water to kill them.
- Try using yellow sticky traps to catch the butterflies. (But you may catch beneficial butterflies as well.)
- Early in the season, cover the plants with a floating row cover or fine netting.
Note: this assumes that the patch is clean and had no infestation carry over from a previous season.
- Spray with an organic insecticidal soap, immediately once the infestation is noticed.
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Note: the advice and information contained herein is based upon our experience and study. As with any advice, please apply at your own discretion.