Pests
Cabbage Root Fly
Identify Cabbage Root Fly: symptoms, possible causes, prevention, and practical actions for 7 affected plants. Wilting of plants
Editorial diagnosis
Diagnosis overview
Cabbage root fly damages brassicas through larval feeding on roots and stem bases.
In gardens, Cabbage Root Fly can occur on plants including Choy Sum, May turnip, Horseradish, Brussels sprouts. In the available profiles, it is linked mainly with Brassicas, Cabbages, Root vegetables. Recorded timing or triggers include May to September.
The recorded risk level is medium. Check roots in wilting young brassicas; do not just water.
Inspect leaf undersides, shoot tips, and the soil around the plant at different times of day. Eggs, larvae, droppings, webbing, or slime trails are often more diagnostic than one damaged leaf.
A common mistake is to treat feeding damage without checking the animal, eggs, larvae, time of activity, and affected plant parts.
At a glance
Plants
7
Category
Brassicas, Cabbages, Root vegetables
Risk
medium
Season
May to September
Scientific name
Delia radicum
Typical signs
- Wilting seedlings
- Chewed roots
- Stunted growth
- Plants pull up easily
Possible confusion
- Similar feeding damage: Always check for insects, droppings, slime, mines, holes, or residues. The damage pattern alone is often not enough.
Immediate actions
- Inspect affected parts and remove where useful
- Stabilise the plant and reduce stress
- Keep monitoring the planting
Prevention
- Encourage vigorous plants
- Monitor regularly
- Support beneficials and diversity
- Adapt care to weather and site