Q: A friend’s house has been invaded with a type of fly or gnat. They are very small and have almost clear wings that begin halfway down their back. They have invaded his kitchen and seem to be coming from the sink area but we cannot find exactly where they are coming from. He was using a spray but I advised him to quit because he was spraying around food and eating utensils. What is the best way to identify and get rid of this pest?

A: I think your friend has drain flies. They are sort of fuzzy so the wings seem to attach far behind their head. If you can observe one at rest, look for its wings held tent-like above its body rather than flat, like a common housefly. Like all of the “filth fly” family, drain flies need a moist, organic site in which to reproduce. The drain of a sink or, more likely, under the rubber guard of a garbage disposal provides a layer of scum in which drain flies lay eggs. Knowing that, the solution is simple: use a brush and soapy water to clean every drain surface you can reach. Once you eliminate their breeding area, the flies will disappear. For more information, check this Web site: www.ext.vt.edu/departments/entomology/factsheets/drainfli.html.