Spotted Wing Drosophila (SWD) is a medium sized fruit fly, generally about 0.08-0.12 inches long. Both SWD and the common vinegar fly have red eyes and an amber-colored body. Two key characteristics distinguish the SWD: Adult male flies have a black spot near the leading edge of each wing tip, and females have a prominent, serrated and saw-like egg-laying device on their hind end that inserts eggs into ripe fruit. Males also have two sets of black combs, which appear as bands on their front legs.
Careful examination is needed to prevent confusing SWD with common vinegar flies. It is highly advisable to use a 30X magnifying glass, small hand lens or head-mounted magnifier to more easily see the key characteristics described above. Being able to look at flies under a microscope will greatly aid in ability to accurately ID female SWD.