Pest identification
What's eating my white onion?
Onion fly (Delia antiqua)
Signs: Plants wilt suddenly; maggots eat roots and bulb bases; entire plants collapse and rot
Control: Grow under insect-proof mesh from sowing; thin carefully (crushed tissue releases odour attracting females); rotate allium family each year
Onion thrips (Thrips tabaci)
Signs: Silvery-white streaks on foliage; papery scarring on outer bulb scales; reduced yield
Control: Apply spinosad or insecticidal soap; use reflective plastic mulch; maintain irrigation to reduce plant stress
Allium leaf miner (Phytomyza gymnostoma)
Signs: White dotted puncture rows on leaves; larvae mine into neck and cause secondary rot
Control: Cover crop with fine mesh in spring and autumn flight windows; remove and bin infested plants
Onion eelworm / stem and bulb nematode (Ditylenchus dipsaci)
Signs: Swollen, distorted, bloated leaves (spikkels); soft neck; bulbs rot from inside; stunted plants
Control: No chemical control available; remove and destroy all affected plants; do not grow alliums on affected ground for at least 3 years
Keep white onion pest-free
Healthy plants resist pests best. Get the basics right:
White Onion pests — FAQ
What is eating my white onion?
White onions face onion fly maggots as the most destructive pest, capable of wiping out a whole row. Thrips scar foliage and bulbs, while allium leaf miner tunnels into necks. Onion eelworm causes distorted growth and has no cure. Birds and rabbits occasionally pull seedlings. Mesh covers are the single best defence.
How do I get rid of onion fly (delia antiqua) on white onion?
Plants wilt suddenly; maggots eat roots and bulb bases; entire plants collapse and rot Grow under insect-proof mesh from sowing; thin carefully (crushed tissue releases odour attracting females); rotate allium family each year
How do I get rid of onion thrips (thrips tabaci) on white onion?
Silvery-white streaks on foliage; papery scarring on outer bulb scales; reduced yield Apply spinosad or insecticidal soap; use reflective plastic mulch; maintain irrigation to reduce plant stress
How do I get rid of allium leaf miner (phytomyza gymnostoma) on white onion?
White dotted puncture rows on leaves; larvae mine into neck and cause secondary rot Cover crop with fine mesh in spring and autumn flight windows; remove and bin infested plants
How do I get rid of onion eelworm / stem and bulb nematode (ditylenchus dipsaci) on white onion?
Swollen, distorted, bloated leaves (spikkels); soft neck; bulbs rot from inside; stunted plants No chemical control available; remove and destroy all affected plants; do not grow alliums on affected ground for at least 3 years