Look for 1-inch long, velvety green caterpillars with a yellow stripe down their back. The imported cabbage worm butterfly is white with dark wing spots and a 1 1/4 inch wingspan. The female butterflies are very active during the day and lay hundreds of yellow-colored eggs on the undersides of leaves.
Broccoli, cabbage, cauliflower, greens and other members of the cabbage family are these pests' Favorite Plants.
Caterpillars chew large, ragged holes in leaves, leaving behind a trail of dark green excrement.
Organic Methods of Control:
Cultural or Mechanical
- Hand pick caterpillars off of plants.
- Use floating row covers on seedlings.
- Interplant mint, sage, rosemary, thyme, or hyssop.
- Use butterfly nets or yellow and white sticky traps to capture female butterflies.
- When possible, grow cabbage plants that are less attractive to caterpillars like red cabbage cultivars.
- Release trichogramma wasps or lacewings.
- Spray with Bt (Bacilus thuringiensis) every two weeks.
- Dust wet plants with lime.
- Spray worms with a solution consisting of 1 ounce of salt to 1 gallon of water.
- Spray with a mixture of soap and lime for three days before harvesting to kill young worms.
- Spray crops with neem as a last resort.