Onion maggot
Onion maggot kills seedlings up to about the three-to-five-leaf stage, and later generations bore into the swelling bulb, which then rots in storage. In New York field trials, three nematode applications over the season cut plant losses and raised yield in two seasons, though the authors say they are not enough to replace insecticide seed treatments and work as an addition to other measures. In a garden, sets survive the first generation better than seed, and cull onions left lying about keep the fly going.
At a glance
- Damage
- Seedlings and transplants that wilt and die; tunnelled roots, bulbs and carrots
- Type
- Root
- Settings
- Garden, Field
- Threshold
- No numeric threshold; yellow sticky cards near the soil show when the flies are flying
- Release
- Steinernema feltiae
- Rate
- About 150 million to 1 billion per acre (≈37k–250k /m²) over two New York field seasons, as a 50:50 mix with H. bacteriophora
How to confirm it
Dig up a wilting plant and look at the roots. Root maggots are white or cream, legless and headless, pointed at the front and blunt at the back, up to about 3/8 inch (9–10 mm), with small brown oblong pupae nearby. Carrot rust fly maggots are slimmer and creamy yellow, in rust-brown tunnels on the carrot surface.
Identification, lifecycle, degree days and every control option are on the full Root maggots profile. Not sure it is this pest? Answer four questions about the damage.
Work it out
How many do I need?
Carries Steinernema feltiae and onion & alliums through so nothing is re-entered. Open the calculator →