Cabbage worm
Leaf nibbler
What it is
Velvety green caterpillars, up to about an inch long, that hide on the undersides of cabbage, broccoli, cauliflower, and kale leaves. They chew large ragged holes and can tunnel into the head.
What you'll see
- Large ragged holes chewed through leaves.
- Dark green pellets of frass on leaves.
- Green caterpillars matching the leaf color, usually along the midrib.
How to prevent them
- Cover plants with lightweight row cover from transplant until harvest.
- Hand-pick caterpillars in the morning.
- Spray Bt (Bacillus thuringiensis) — safe for bees, only affects caterpillars.