Cabbage worms can be a major nuisance in the garden, but with a little bit of know-how, they can be easy to identify and control. In this guide, we’ll tell you everything you need to know about cabbage worms, including how to identify them, what damage they cause, and how to get rid of them. Keep reading to learn more!
Worms are the larvae, or the immature stage of any of a number of insects. This includes various moth and butterfly species. However, some varieties of beetles commonly produce worms that are nearly indistinguishable in general appearance and feeding habits from moth larvae.
Types of Cabbage Worms
The three primary culprits that attack brassicas plants in North America are cabbage worms (AKA diamondback moth), imported cabbage worms, and the cabbage looper.
These worms feed on cabbage and other cruciferous vegetables such as cauliflower, Chinese cabbages, garden cress, watercress, broccoli, brussels sprouts, kale, kohlrabi, mustard greens, radishes, and turnips.
Imported Cabbage Worm
Imported cabbage worms are the most commonly found species in home gardens. The larvae are a white butterfly with black spots. They are well established from Canada to Southern California.
The larvae / worms are a velvet green with faint yellow stripes along their sides.They feed on all members of the brassica family.
Cross-Striped Cabbage Worm
The cross-striped cabbageworm lays its eggs on the lower leaf surfaces. The worms / caterpillars [larvae] reach about 3/4 inches long. They are light blue-gray on top and green on their bottoms. There are multiple black stripes on their backs and a yellow line down their sides.
Cabbage looper larvae are a light green color with faint stripes down their backs. They reach approximately 1.5 inches long and have three pairs of slender legs near the head and three pairs of larger legs at the rear end. The middle section is legless and is looped when the insect is moving. (Inch-worm style.
The celery worm also known as carrot caterpillar and parsley worm does not feed on cabbage or other brassicas but is a prolific pest of similar crops -which include carrots, celery, parsley, dill, and parsnip. They chew the foliage and stems and destroy green tops.
Parasitic Wasps, Ground beetles, syrphid fly larvae, spiders. Lady Bugs, Praying Mantid.
Spinosad is another biopesticide , correctly termed a microbial pesticide, harmless to humans. Spinosad will interfere with pollinators as well as pests – evening / night time use is advisable.
Bt – bacillus thuringiensis. – Diamond Back Moth has developed some resistance to it – has proven effective against garden worms , it is a bacterium / organic pesticide that is readily available to home gardeners. It’s harmless to people and pets. It’s not a miracle cure but as stated , it is highly effective. Apply it at either bloom or petal fall, or both. Bt It is a stomach poison and must be ingested . It is more effective when applied during warm, dry weather while the larvae are actively feeding. Bt breaks down quickly in nature so multiple treatments per season are necessary.
Neem and various derivatives of their active ingredient Azadirachtin are an effective Biopesticide that works by interrupting the insect’s growth cycle resulting in its early death.
Diazinon can be applied at petal fall, but is not as eco-friendly as the bio-pesticides listed above as it is toxic to beneficial insects and pollinators. Other Broad-spectrum insecticides, such as pyrethrin or malathion only as a last resort, generally used commercially and not really advisable for smaller plantings or home gardeners.
Most Sprays/Pesticides must be applied in the pre-bloom stage to prevent injury. Do not apply insecticides, even bio-pesticides during bloom time to protect vital pollinating insects.
Related: Controlling Leafroller Caterpillars