Pests
Onion fly
Identify Onion fly: symptoms, possible causes, prevention, and practical actions for 7 affected plants. Wilting and yellowing of leaves
Editorial diagnosis
Diagnosis overview
Onion fly attacks onions, leeks, and related crops at the base and roots.
In gardens, Onion fly can occur on plants including Garlic, Allium, Welsh onion, Shallot. In the available profiles, it is linked mainly with Alliums, Herbs.
The recorded risk level is medium. Remove affected young alliums with a soft base.
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
Alliums, Herbs
Risk
medium
Scientific name
Delia antiqua
Typical signs
- Yellowing leaves
- Wilting
- Soft base
- Gappy rows
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
Affected plants
Guides
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