Pests and Diseases: Cabbage Worms

Have you noticed the onslaught of white butterflies flitting aroung your garden? It seems that they’re everywhere this spring but they’re particularly noticeable around the veggie garden. There’s a good reason…they’re after our cabbage. The butterfly is the adult version of the cabbage worm.

cabbage worms
Photo courtesy of Utah State


But it’s not just cabbage that they’re after…they enjoy all members of the Brassica family which includes cauliflower, broccoli, collards, kales and other salad crops. The larval form is the one that really does the damage. It’s green in color and is easy to miss when quickly glancing at your plants. If you see holes in the leaves of your plants, flip over a few leaves and see if this guy is hanging around:

cabbage worms
Photo courtesy of University of Maryland



If you only have a few plants to monitor, hand picking and squishing is the easiest method; it also has the least amount of negative impact on the environment…unless of course you’re a cabbage worm. If you can’t bring yourself to squish them, carry a small bucket or mason jar full of soapy water and just drop them in when you see them. If you have chickens, offer the cabbage worms to your flock as a tasty, high protein snack.

Floating row covers are especially effective at deterring the moth from laying its eggs in the first place. If you grow rows of brassicas, applying floating row covers before you see the moths will reduce your population of cabbage worms to virtually zero. If you’re not familiar with them, floating row covers are comprised of lightweight woven fabric that still allows the sunlight through. They are a great physical barrier to keep the butterflies away from your cabbage.

If the number of cabbage worms is too great for you to hand pick, you can spray Bt to control them. Bt (Bacillus thuringiensis) is a bacteria that only affects caterpillars so you don’t need to be concerned with assaulting your beneficials like ladybugs and lacewings. Just be aware that Bt is not effective on the adults or the eggs…it only works on the caterpillar stage of the cabbage worm life cycle.

Have you seen the white butterflies flitting around your garden this year? Have you noticed any cabbage worms? If so, what methods do you use to control them? Leave me a comment below or send me an e-mail. (I’m going to stop putting my e-mail address in the posts…the spam is eating me alive!) If you enjoy being part of the Mid-Atlantic Gardening community, join our e-mail list (upper right hand corner of this page), become a fan on Facebook and follow me at Twitter. Happy gardening!