Cabbage worms are the larvae of white butterflies that feed on cabbage, broccoli, kale, and other brassicas. To get rid of them, hand-pick worms off plants and drop them in soapy water. Use Bacillus thuringiensis (Bt) or spinosad for effective biological control. Use floating row covers to protect plants from egg-laying butterflies. Plant companion plants like dill, mint, or marigolds to repel them. Introduce natural predators like parasitic wasps. Prevention is key: remove plant debris, rotate crops, and inspect plants regularly. Cabbage worms are most active in spring and fall.
What you will need
Identify Cabbage Worms and Signs of Damage
What they look like: Green, velvety caterpillars (1-1.5 inches) with a faint yellow stripe down the back.
What they become: The adult is a white butterfly with black spots (cabbage white butterfly).
Signs of damage: Chewed leaves, irregular holes, dark droppings (frass) on leaves.
Common hosts: Cabbage, broccoli, kale, cauliflower, Brussels sprouts, and other brassicas.
When they're active: Spring and fall. Butterflies lay eggs on brassica plants.
Hand-Pick Cabbage Worms
How it works: Hand-picking removes worms from plants, reducing the population.
How to do it: Check plants regularly and pick off worms. Drop them in a bucket of soapy water.
Where to look: On leaves, stems, and the undersides of leaves.
Frequency: Check your plants daily during the growing season.
Tip: Look for dark droppings (frass) on leaves—they indicate the presence of worms.
Use Bacillus thuringiensis (Bt)
How it works: Bt is a naturally occurring bacterium that produces a toxin that kills caterpillars when ingested.
How to use: Apply Bt to brassica plants when worms are actively feeding.
Application: Follow label instructions. Apply every 5-7 days.
Benefits: Bt is safe for beneficial insects, pets, and humans.
Timing: Apply in spring and fall when worms are active.
Apply Spinosad
How it works: Spinosad is a natural insecticide derived from soil bacteria. It kills cabbage worms on contact and by ingestion.
How to use: Apply to brassica plants in the evening when worms are active.
Application: Follow label instructions. Apply every 5-7 days.
Caution: Spinosad can harm bees—avoid applying during flowering.
Timing: Apply when worms are actively feeding.
Use Floating Row Covers
How it works: Row covers create a physical barrier that prevents butterflies from laying eggs on plants.
How to use: Drape row covers over plants and secure the edges with soil or rocks.
Best for: Young plants and early in the season.
Benefits: Row covers also protect from other pests and frost.
Use Companion Planting
Dill: Dill attracts beneficial insects that prey on cabbage worms.
Mint: Mint repels cabbage worms and other pests.
Marigolds: Marigolds deter many garden pests, including cabbage worms.
Benefits: Companion planting is a natural, long-term pest control strategy.
Introduce Natural Predators
Parasitic wasps: Small wasps that parasitize cabbage worms, killing them.
Birds: Many birds eat cabbage worms. Provide bird feeders and birdbaths.
Ground beetles: Ground beetles eat cabbage worms and their eggs.
How to attract: Plant flowers to attract beneficial insects and provide habitat.
Benefits: Natural predators provide long-term, sustainable control.
Prevent Future Cabbage Worm Problems
Rotate crops: Don't plant brassicas in the same spot for 2-3 years.
Remove plant debris: Remove plant debris where cabbage worms may overwinter.
Use row covers: Protect plants with floating row covers.
Monitor: Check plants regularly for signs of cabbage worms.
Companion planting: Plant dill, mint, and marigolds near brassicas.
Common problems and fixes
| Problem | Likely cause | What to do |
|---|---|---|
| Cabbage worms returning quickly | New eggs hatching or re-infestation from nearby plants. | Use row covers and Bt. Check plants daily. |
| Bt not working | Applied too late or not enough coverage. | Apply early when worms are small. Spray thoroughly. |
| Cabbage worms in greenhouse | Butterflies entering the greenhouse. | Use screens and row covers. |
| Worms eating broccoli heads | Cabbage worms hiding in broccoli heads. | Soak broccoli in salt water before cooking to remove worms. |
Gardener's checklist
Test what you learned
What do cabbage worms look like?
Answer: Green, velvety caterpillars
What is the most effective natural control for cabbage worms?
Answer: Bt (Bacillus thuringiensis)
What prevents butterflies from laying eggs on cabbage?
Answer: Floating row covers
What companion plant repels cabbage worms?
Answer: Dill
What are cabbage worms the larvae of?
Answer: White butterflies
Common questions
Can cabbage worms kill plants?
Yes, a severe infestation can defoliate plants and reduce yields.
Are cabbage worms harmful to humans?
No, cabbage worms are not harmful to humans. They only affect plants.
How do cabbage worms get into the garden?
White butterflies lay eggs on brassica plants. The eggs hatch into cabbage worms.
Does neem oil kill cabbage worms?
Neem oil can be effective, but Bt (Bacillus thuringiensis) is more specifically targeted to caterpillars.
How do I prevent cabbage worms naturally?
Use floating row covers, hand-pick worms, apply Bt, plant companion plants (dill, mint), and rotate crops.
Cabbage worms are common pests of brassica plants, but you can control them with a combination of methods. Hand-pick worms off plants and drop them in soapy water. Use Bt (Bacillus thuringiensis) or spinosad for effective biological control. Use floating row covers to prevent butterflies from laying eggs. Plant companion plants like dill, mint, and marigolds to repel them. Remove plant debris and rotate crops to prevent future infestations. With persistence and a multi-method approach, you can keep cabbage worms from damaging your garden.
Frequently asked questions
How often should a vegetable garden be watered?
Frequency depends on weather, soil and plant size. Check the soil rather than watering on a rigid schedule.
Is compost enough fertilizer?
Compost improves soil and provides nutrients slowly. Heavy-feeding crops may still need additional feeding.
The Sproutstead Editorial Team
We create clear, practical gardening and homesteading guides designed for real homes and beginner growers.
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