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.
Flush floor drains on a regular basis and repair plumbing leaks and seepage. Keep all garbage in sealed trash bags and take out daily. Traps can be used but different flies use different attractants and some traps only attract flies from outside. Traps only capture individuals and will not replace identifying and cleaning the breeding site. Chemical control Chemicals only kill adult flies and do not deal with the source of the problem.