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Walnut Husk Fly

Walnut husk fly Walnut husk fly larva
Walnut husk fly

Hosts: apricot, nectarine, peach


Biology:
  The walnut husk fly is a tephritid fruit fly like the apple maggot and western cherry fruit fly.  The adults are about the size of a house fly and have patterned wings with an inverted “V” at the tip.  It lays eggs in the husk of walnut after the husk has softened a bit.  It will also lay its eggs in softening peach and nectarine fruits, especially where husk fly numbers are elevated due to the presence of non-treated walnut trees.   Larvae (maggots) feed within fruits. 


Symptoms:
  Small maggots inside peach/nectarine or apricot fruit.


Monitoring:
  Yellow sticky traps baited with ammonium carbonate.

Treatment Threshold:  No threshold determined.


Degree Day Model:
  None


Management Considerations:
  Treat by 7-10 days after the first adult flies are caught or beginning in late July.