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.