Cabbage Root Maggots: Identification, Control & Prevention

Cabbage root maggots (larvae of the cabbage root fly) attack cole crops: cabbage, cauliflower, broccoli, Brussels sprouts. Other root maggots target carrots, onions. Prominent in northern zones; difficult to control as they feed underground—often detected only by stunted growth or wilting.

Identification

• Maggots: white, legless, ~1/3", clumped on roots.
• Adult fly: tiny, gray, fragile; emerges early spring.
• Eggs: 1/8", oblong, laid in rows near stem base in moist/shaded soil.
• Lifecycle: eggs → larvae (feed on roots) → pupae → adult flies.

Damage

Wilting, bluish/yellow cast to foliage. Plants shrivel; maggots visible on roots when pulled. Death is common. Worst damage in late summer.

Control

• Scout for eggs when flies active; destroy by hand.
• Cabbage collars (cardboard skirts) block egg-laying.
• Sticky traps catch adults.
• Beneficial nematodes or parasitic wasps (biological control).
• Dig plants, swish roots in cold water to remove maggots; drown or feed to chickens.
• Check local extension for chemical options.
• Old remedy: tar paper smell repels.

Prevention

• Red cabbage varieties show resistance.
• Floating row covers at transplant (seal edges).
• Late planting to miss peak fly emergence.
• Crop rotation.
• Fall/spring tilling exposes overwintering pupae.
• Trap crop: radish attracts maggots; destroy infested plants.

Plants Affected

• Cabbage
• Cauliflower
• Broccoli
• Brussels Sprouts