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/Damage

Small maggots inside peach/nectarine or apricot fruit; small brown tunnels in 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.