Apple Maggot

Infested apples – Note bumpy or misshapen appearance of fruit and brown tunnels in the flesh

Photo by H.J. Larsen, Bugwood.org

Apple Maggot adult fly – Note zigzag wing pattern

Photo by Joseph Berger, Bugwood.org

Causal Organism: Rhagoletis pomonella

Crops Affected: apple, crabapple, hawthorn, sweet cherry, sour/tart cherry, asian & common pear, bitter cherry, common plum, spreading cotoneaster, etc.

Life Cycle:

  • One complete generation per year
  • Adult flies emerge in late June to early July and continue to live through to early October
    • Upon emergence, adults feed on dung, honeydew, and plant exudates (saps, oozes, nectar) for 7-10 days until they are mature and then mate
  • Females lay eggs on ripening fruit over a 2-4 week period
    • Eggs are laid singly under the skin of the fruit
    • Eggs hatch within 3-7 days
  • Larvae burrow through the fruit until they mature
    • This can take between 2 weeks to 7 weeks
      • The rate of development is dependant on temperature
    • Larvae leave the fruit when they are mature and burrow into the soil to pupate and overwinter
      • This is often after it has dropped to the ground

Symptoms:

  • Larval feeding / burrowing within the fruit results in brown channels in the flesh of the fruit
  • Infested fruit is often misshapen and may appear bumpy
  • Black spots, small dimples, or depressions may be visible where egg laying has occurred
  • Infested fruit often drops prematurely

Monitoring:

  • Use ammonium carbonate-baited yellow sticky or red sphere sticky traps put out before mid June to monitor for adults
    • The sticky material on the trap surfaces should be replaced regularly
    • Ammonium carbonate is placed in a plastic container with a puncture and should be refreshed every 7-10 days
  • Place traps regularly throughout the planting
  • Assess traps for the presence of Apple Maggot adults (there are other species which resemble AM)
  • Regularly inspect fruit for infestation symptoms

Management:

  • Chemical controls are available for use in commercial operations
    • These should be used in conjunction with monitoring for adults
  • Remove wild plants within 500m of any established orchard
  • Remove and destroy infested fruit from the trees
  • Collect and dispose of dropped apples right after they fall, to prevent larvae from emerging and pupating – Sanitation is CRITICAL
  • Placing a tarp under a tree with a history of infestation may prevent the emerging larvae from fallen fruit from entering the soil

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