How to identify
- Wilting onion seedlings in patches
- Soft, rotting bulbs with white maggots inside
- Damage worse in cool, moist springs
Damage: Stand loss and rotting bulbs in storage.
Control methods
- Row cover from sowing until midseason.
- Rotate allium beds; do not compost infested bulbs.
- Plant in well-drained soil; avoid overwatering seedlings.
What products to use
We list product types and what to check on the label — not brand rankings, prices, or “we tested” claims. Always follow the label for your crop, and prefer the least disruptive option that works.
Row cover / insect netting
When: Any bed with a history of onion maggot
Look for: Sealed edges; remove only for necessary weeding, then replace