Plants in the cabbage family, also known as brassica, are an important part of Southern California Winter gardens. Brassica family members such as broccoli, cauliflower and brussels sprouts are the namesake for a common winter pest: the cabbage looper.

The cabbage looper is the larval stage of an innocuous looking grey moth.  In your garden, they appear as small green worms that munch holes in your brassica plants and greens.  Loopers are easy to identify by their distinctive way of moving.  The worms move slowly by curving their back into a half-oval as they move their back legs forward, creating a small arch. 

Cabbage Loopers are extremely common, but they are often missed in the garden because of their ability to camouflage themselves. They hide on the underside of leaves or along stems.  This hiding tactic and their green coloring makes them difficult to spot.  If you see their trademark ragged chew holes in your leaves, carefully inspect the undersides of a leaf until you find the offending worm.  

Hand picking is very effective at controlling cabbage loopers, but you must be extremely diligent about inspecting your brassica for these pests. If your infestation is particularly severe, control their population by attracting or importing natural predators such as praying mantids and parasitic wasps. Parasitic wasps will lay small white eggs on a Cabbage Looper’s back, and their larvae will emerge to feed on the worms.  If you see a Cabbage Looper with such eggs, you should leave it in the garden to promote beneficial insect populations.

If you are unable to control these worms through hand picking, there are several organic pest control products that will limit their damage, including garlic oil and BT.  

Learn More:

UC Davis Pest Management Guidelines: Cabbage Looper. 

Note: This post originally appeared in the March-April 2010 issue of Farmscape's newsletter, Bountiful Harvest.  Sign up for the newsletter using the "Quick Contact" form on the top right of this page.

Image courtesy Flickr user Magic Madzik, Creative Commons.