Apple maggot

The apple maggot (Rhagoletis pomonella), also known as railroad worm, is a pest of several fruits, mainly apples. Before the arrival in America of apples from Europe, it was found mainly in hawthorns.

The adult form of this insect is about 5 mm (0.20 in) long, slightly smaller than a house fly, with a white dot on its thorax and a characteristic black banding shaped like an "F" on its wings. When threatened it turns its wings 90 degrees and moves them up and down whilst walking sideways; the combination mimics the appearance of it being a spider due to the wing pattern in the new position appearing as additional legs. The larva, which is the stage of this insect's life cycle that causes the actual damage to the fruit, is similar to a typical fly larva or maggot. Other "worms," especially the larvae of the codling moth, that infest the insides of apples are often confused with the apple maggot. Generally speaking, however caterpillars often feed in the apple’s core while apple maggots feed on the fruit flesh. In infested fruit, the larvae are often difficult to detect due to their pale, cream colour and small body size. The maggot stage has many enemies, including several braconid wasps: Utetes canaliculatus, Diachasmimorpha mellea, and Diachasma alloeum.