The apple maggot belongs to a family of fruit flies (Tephritidae) that can infest a wide variety of fruits. The adult is about the size of a house fly and the dark banded pattern on its wings forms the letter “F.” Its native host in the western U.S. is the wild or black hawthorn. In Utah, apple maggot has not been reported in commercial orchards, and only sporadically in backyard plums and apples.
This pest is particularly important to commercial orchardists because it is regulated by a quarantine to prevent its spread. If the insect is found to be active in an area, the Utah Department of Agriculture and Food may require home orchardists to place yellow sticky card traps (Pherocon AM®) to determine the insect’s abundance. For more information on tephretid fruit flies, see “western cherry fruit fly.”
Adults lay eggs in apples or cherries in summer; maggots drop to pupate in soil. Apple maggot overwinters as pupae in the soil. They emerge as adults in early summer, over a period of one to two months. Adult females start laying eggs 10-14 days after emergence, and can lay up to 200 eggs. Eggs are laid inside the fruit, and the developing larvae feed for up to 15 days before dropping to the ground to pupate.
- Dimpled apples, with cone-shaped pits
- Narrow brown tunnels in apple flesh
- Small pits indicating egg-laying scar
- Collapsed fruit
This pest is regulated by a quarantine to prevent its spread, so if found, it must be treated. Insecticides is the only option, and includes malathion, carbaryl, and acetamiprid. Tarps laid under infested fruit trees can prevent larvae from burrowing into the soil. (Discard contents at the end of the season.)
Hang red sticky sphere traps or yellow sticky cards starting in early July and check traps weekly.
According to Cornell University, treat when 5 flies are caught per trap.
- Residential: imidacloprid (systemic), carbaryl, or permethrin
- Commercial: click here