Apple Maggot, Rhagoletis Pomonella (Walsh)

The apple maggot, Rhagoletis pomonella (Walsh) is an insect native to North America which originally fed in the fruit of wild hawthorn (Crataegus spp.). During the past 100 years it has become a primary pest of cultivated apples, especially in the northeastern United States and southeastern Canada. Summer-and early fall-maturing varieties are particularly vulnerable, but hard winter apples are sometimes infested. Thin skinned sweet and subacid varieties are most susceptible, but acid varieties may be attacked. Plum, pear, and cherries also serve as hosts, but usually the apple maggot is not a serious pest of these fruits. Crab apples are invariably infested by this pest. A closely related species, the blueberry maggot (Rhagoletis mendax Curran), is important as a pest of cultivated blueberries.

Injury to fruit is caused by whitish or yellowish, legless maggots about 1/2 inch in length and tapering toward the head. These maggots bore throughout the fruit, forming irregular, winding tunnels which turn brown, often causing premature dropping of fruit. When the fruit is slightly infested, there may be no external indication of the presence of the maggots, but when the fruit ripens, the burrows show as dark, winding trails beneath the skin. Minute egg punctures and distorted, pitted areas may show on the surface. Heavily infested early varieties of fruit will be reduced to a brown rotten mass filled with the fly larvae.