Pest: Cabbage Worm
Cabbage worms are very common on cabbage plants and their relatives. Often times you spot their damage before their camouflaged bodies.
Cabbage worms are light green with a faint yellow stripe down their side. They blend in very well. They measure about 1” long and have fine velvety hairs on their surface. The adult butterflies have a 1-2” wingspan and are whitish-yellow with black splotches on their wings.
Life Cycle
The cabbage worm is the larvae. After 2 to 3 weeks of feeding, larvae pupate attached by a few strands of silk to stems or other nearby objects. The adult is a butterfly. The whitish, rocket-shaped eggs are laid singly on the undersides of leaves. They spend the winter underground as a chrysalis.
Plants They Attack
They enjoy all members of the Brassica family, including: broccoli, cabbage, cauliflower, kale, kohlrabi, radish, and turnip.
Spot the Damage
They chew ragged holes in leaves. They may also attack flower clusters of broccoli and cauliflower, leaving round holes scattered throughout. Small cabbage worms are often difficult to spot, so check the undersides of leaves and along the leaf veins. Their presence if often noted by the dark pellets of excrement they leave behind.
Preventative Actions
- Turn over the garden soil in the fall, exposing any chrysalises to winter freezes and predators.
- Choose cabbage varieties with tighter heads as they are less susceptible to damage.
- Cover susceptible plants with floating row cover, making sure to seal the edges with dirt so pests can not get in.
- Hand-pick worms off the plants, placing them into soapy water.
- Sprinkle plants with corn meal or rye flour. The worms will eat it, bloat, and die.
- Soak Brassica crops in warm salt water before cooking to prevent consuming any of the bugs.
Organic Product Controls
Use BT, botanical oils, citrus oils, pyrethrins, spinosad.
Sources
CCF staff
Good Bug, Bad Bug by Walliser 2008
The Organic Gardener’s Handbook by Ellis and Bradley 1996
Interested in learning more? The Grower’s Library at Johnny’s Selected Seeds may have the information you’re looking for.