Onion fly

Young onions, leeks and shallots turn yellow, flop over and wilt. White maggots sit in the bulb or stem base, and the bulb rots.

From May, the onion fly lays its eggs near young onions and leeks; onions grown from seed are the most vulnerable.

What can you do?

1. Pull up affected plants with the soil around the roots and put them in the general waste so the maggots can’t pupate.
2. Cover onions and leeks with fine insect mesh, well secured at the edges.
3. Plant onion sets rather than growing onions from seed; sets are less susceptible.

Prevention

Rotate every year and keep the plants under mesh from May to July. Avoid damaging plants when weeding, as the scent attracts the fly.

When to watch out: May–August

Diseases and pests · All species