How to eliminate little green caterpillars

There is little that is as distasteful as finding a thoroughly steamed green caterpillar in your broccoli or cauliflower on your plate!!!

These little green caterpillars are the product of two common flying insects. The Imported Cabbage Butterfly is one of these insects. It is white with small black wing markings and are easy to see now as they feed not only on garden cabbage, broccoli, cauliflower and similar cole crops but also on canola which is of the same plant family. The other culprit for producing the worms is the Cabbage Looper Moth. It is a small “miller”-type of moth that is most active in evening hours. It is mottled brown in appearance.

There are a couple of choices for eliminating the caterpillars. The first is the insecticide Permethrin which is a fast-acting insecticide with a very short effective kill period. This will kill any insects that it comes in contract. It is mixed with water in a sprayer and sprayed on the plant. Since Permethrin has no residual control, reapplication may be needed to control later infestations.

The second choice is one which only kills caterpillars and nothing else. It is a natural occurring bacteria which kills only caterpillars by paralyzing their digestive system. It is safe for other insects, birds, animals and people. It comes as both a powder to sprinkle on the leaves and as a concentrated liquid which is mixed with water and sprayed on the leaves. If using the powder, wetting the plants lightly before applying will help the powder to stick to the leaves where the caterpillars will eat it and die. It is neutralized by sunlight, so applying in late afternoon or evening will improve control.

Whichever control method you use, be sure to read all of the product label before use. Always follow all label directions and warnings.

Ken Eraas is the Ward County Extension Horticulture Assistant. You can reach him by calling 857-6444 or emailing