Are Drain Flies Harmful? In short, no, drain flies are not harmful to humans. Though drain flies consume and live in sewage and bacteria, they are not disease-carrying insects, but In great masses, they can carry the bacteria with them.

Can drain fly larvae make you sick?

These pests are a nuisance because they infest in large numbers. Once inside, drain flies may plug pipes and spread bacteria from the filth they live in, possibly contaminating food in the process. These pests, even though they live in filth, are not known to spread any disease to humans.

Are drain fly worms harmful?

Drain worms are not potentially harmful because they do not bite or transmit disease to humans. ... In some cases, drain fly larvae have been known to worsen bronchial asthma.