Onion fly

Adult Delia antiqua (dorsal view). Image: Simon Hinkley & Ken Walker, Museum Victoria, PaDIL

  • Onion fly affects onions, shallots, leeks, garlic, chives, Japanese bunching onions and Welsh onions.
  • Adults are about 7mm long, yellowish grey with five dark stripes on the thorax, yellowish wings, black legs and antennae, similar in appearance to a domestic fly.
  • Eggs are dull white with long white stripes
  • Larvae are white maggots which reach 8mm when development is complete.
  • Damages bulbs, leaves, roots, seedling.
  • Look for yellowing and wilting of the host’s outer leaves. Green and apparently healthy leaves will become floppy, and the whole plant may collapse. Later generations of larvae tunnel into the onion bulbs as well as attack the roots.
  • Spread by infested soil and plant material.


High priority pest of: Onions, Vegetables

Scientific name: Delia antiqua
EPPRD Category:
Life Form: Flies & Midges (DIPTERA)

Pest Documents

FS: fact sheet

CP: contingency plan

DP: diagnostic protocol