Onion fly
Pest Maggots that eat the roots and bulbs of onions, leeks and shallots.
What to look for
Seedlings or young plants turn yellow, flop and wilt. Small white maggots feed inside the bulb or at the base of the stem.
When: May to June, with a second wave in late summer.
How to prevent it
- Cover plants with fine mesh from planting, with the edges buried.
- Grow from sets rather than seed, as they are less likely to be hit.
- Rotate onion crops each year.
How to deal with it
- Remove and bin affected plants, including the maggots.
- Raise new onions in a different bed.
Crops it affects
If you choose to use any treatment, use only products approved for UK home gardens, follow the label and avoid spraying open flowers. See all pests and diseases.