There are many types of flies that can emerge from your pipes and many reasons why these small black flies suddenly invade your
property. Your piping may have been disturbed or you may have a problem with
your u-bends. They may only appear in one room or may seem to invade the whole
house. One thing is for sure, just swatting them or fly spraying them will
not sort out the problem at source and they will return. So although they may seem to have
disappeared and any occurrence however small, indicates a problem and without the
right treatments they will return and maybe every year.
The key to fly control is eradicating the pests. This simply means killing the adult flies so that they don't have the opportunity to breed.