Flies can be broken into two basic categories: large flies and small flies.
Examples of large flies include the typical House Fly, along with less common Blow Fly and Flesh Fly. Sometimes large flies are called ‘filth flies’, as they generally lay eggs on garbage, manure, or dead animals. They can then land on food intended for human consumption, or on food preparation surface. This in turn can spread diseases or parasites. As such, large fly problems need to be dealt with quickly. If you are seeing high numbers of large flies suddenly in your home or business, this can be an indicator that an animal, such as a rat, has died in your walls, attic, or crawlspace.
Examples of small flies include fruit flies and drain flies. Everyone is familiar with fruit flies, but drain flies are often mistaken for fruit flies. Drain flies are breeding on the organic buildup, or ‘gunk’ that has built up over time in a drain. To get rid of drain flies, the drains should be treated with a special organic cleanser, and then scrubbed to remove the buildup that the flies are breeding in. If it is fruit flies instead, the cause is usually a different sanitation issue. Your garbage can may need to be cleaned on the inside. There may have been a spill in an area you don’t see often. Ripening fruit is also a common cause of the fruit flies presence, and putting the fruit into the fridge can remedy the situation.