A.  The specific "worms" you are most likely referring to are known as cabbage loopers, so-called because caterpillars tend to crawl with a distinctive "looping" motion. The "worms" (this stage is more correctly termed as the larva or caterpillar stage) grow to be about 2 inches long and are light green in color. The caterpillars have three pairs of "true" legs behind the head in addition to three pairs of thick or fleshy "false legs" located near the back segments of the body. The adult stage is a moth which is a mottled grayish-brown with a 1.5-inch wingspan.

In addition to cabbage and broccoli, the caterpillar stage of cabbage loopers also feed on leaves of a wide variety of other plants including beets, carnations, kale, lettuce, nasturtiums, parsley, peas, potatoes, soybeans, spinach, and tomatoes. Be aware that caterpillars have chewing mouthparts. Injured leaves typically appear tattered, with irregularly shaped holes removed between major leaf veins.

Satisfactory control can be obtained using a product containing Bacillus thuringiensis, commonly referred to as Bt. This is a biological type insecticide which gives excellent control of a wide variety of caterpillars. It is sold under a variety of trade names, such as Dipel, BioWorm Killer, and Thurgicide.

For this material to be effective, it must be eaten by the caterpillar. Please note that the caterpillars will stop eating very soon after ingesting this product, but death will occur about 2-to-3 days afterwards. This is a relatively safe and very effective insecticide and can be used for control of most types of caterpillars on most commonly grown garden vegetables.

Cabbage loopers can also be controlled with other insecticides such as liquid Sevin, pyrethrin or rotenone. Through coverage of the plant is important. If only a few worms are found, they can be handpicked and removed from the site.

Check your garden regularly for best control. Remember, whenever using any insecticide or other pesticide, always be sure to read and follow directions provided on the pesticide label.

Cabbage loopers can inflict serious damage on cabbage plants.

Cabbage loopers tend to crawl with a distinctive "looping"
motion, hence their name. Caterpillars have three pairs
of "true" legs and three pairs of thick or fleshy "false legs."

Cabbage loopers also feed on leaves of broccoli (shown above)
as well a wide variety of other plants including beets, kale,
lettuce, parsley, peas, potatoes, spinach, and tomatoes.