Fruit flies breed in yeast associated with moist, fermenting organic material in trash cans, recycling bins, compost and sour mops. Drain flies breed in floor drains, sink overflows, and unused urinals, sump pumps and sewers. Filth flies such as houseflies and blowflies breed in garbage and animal waste. They do have a public health concern as they are capable of mechanically transmitting a number of diseases. Fungus gnats breed in potting soil of indoor plants and in moist organic matter.
Cluster flies seek shelter in buildings during the fall.
Indoors electric fly traps can be used in food or storage areas. Traps work better in dark corners, false ceilings and other sites away from light. Fly paper and fly swatters can be used for individual flies. Keep trash containers upwind of school, dump once or twice a week, and keep clean. Sour milk is very attractive to house flies.