Biology: Adults lay eggs in apples or cherries in summer; maggots drop to pupate in soil.
Symptoms: Knobby apples with cone-shaped pits; narrow brown tunnels in apple flesh.
Monitoring: In Utah, this fly has been trapped in backyard apple and plum trees, and maggots have been found in plums but not in apples. In Colorado, it is found in apples from Colorado Springs to Loveland, CO. Apple maggot has not been trapped in commercial orchards in Colorado, Utah, or Idaho.
To monitor, hang red sticky sphere traps starting in early July or at orchard borders.
Treatment Threshold: According to Cornell University, treat when 5 flies per trap are caught.
Degree Day Model:
- Lower threshold: 44°F
- Adults active at 1450 degree days after March 1
Management Considerations: This pest is regulated by a quarantine to prevent its spread.