Apple Maggots infest apples, plums, pears, apricots, hawthorns, and crabapples. Highly adaptable, they have also been found in pyracantha and cotoneaster. Apple maggots are prevalent in the Midwestern and eastern United States and in eastern Canada: they are also found in California, Oregon, and Washington. These pests appear in July; females lay their eggs under the skins of apples; eggs hatch in 5-10 days and the maggots feed on apple flesh leaving brown tunnels and eventually rotting the fruit. The larvae are generally cream colored and 1/3" long at their full size. The adult female is about the size of a house fly with a black abdomen striped with four white bands.
Control options begin with trapping and monitoring with Yellow Sticky Traps or Apple Maggot Traps. Place these in your fruit trees when the adults are emerging to keep track of infestation levels and to reduce the reproduction cycle. At the same time it is recommended that releases of the beneficial insect, Trichogramma spp begin. Depending upon how many generations occur during the growing season, you may need to make 3 or more releases per season.
Since there are some eggs that may overwinter, it is a good idea to spray trees with horticultural oil during the dormant season. This needs to be done when temperatures are above freezing and before they get to 88° F.
The control products are listed below. For more information about fruit tree care please see Fruit Tree Care.