The apple maggot fly, with its glossy black body, yellow legs and transparent wings, is a colorful but unwelcome addition to the insect life of apple-growing regions throughout North America, but especially in the Eastern United States, northern California and Canada. Females of the species like to give their young a safe and tasty start in life by boring holes into healthy apples and inserting a single egg into each perforation. Once hatched, the newborn maggot burrows its way through the fruit as it feeds and develops, leaving a network of irregular brown tunnels in its wake. Outwardly, these subsurface tunnels show up as a series of dark, vein-like lines on the skin of the infested fruit, which may also have a dimpled appearance and will often fall to the ground. Fallen fruit should be picked up and disposed of immediately as the pre-adults inside will continue develop if left undisturbed. Infestation takes place throughout the summer and into early fall, with sweet-fleshed apple varieties (such as Red Delicious) typically suffering the most damage.