Are Drain Flies Harmful?

If you have a kitchen, whether it’s in your home or in your restaurant or commercial establishment, flies buzzing around your bathrooms or food prep stations can be embarrassing — or costly, if you’re fined for violations by a health inspector. The common house fly and bottle fly are widely known, but if you’ve ever seen what looks like a cross between a moth and a fly, you’ve probably encountered a drain fly. We can all agree that it’s never pleasant to deal with a fly problem, but are drain flies harmful?

Below, we explain how to identify drain flies, where they come from, and some of the risks of leaving your drain fly problem untreated.

What Are Drain Flies?

Drain flies, also known as sewer flies or moth flies, are tiny gnat-like insects that are considered “true flies” because they only have one set of wings. They are commonly found in areas with damp and organic material, such as sewers, compost bins, moist soil, and of course, drains. Drain flies are small insects, like fruit flies, but with fuzzy wings like a moth’s. They have a short lifespan of around two weeks and are most active during the evening.

These flies are considered nuisance pests because they can congregate in large numbers inside the home. They are attracted to the moisture and bits of food found in drains and pipes, and will lay their eggs in these moist areas so drain fly larvae feed on the drain’s organic matter as they hatch.

Drain flies typically only live for a couple of weeks, but each drain fly can lay several hundred eggs in their lifetime. These eggs hatch, become adult drain flies, and start reproducing within 2 weeks, so an untreated drain fly infestation can quickly get out of hand.

How Are Drain Flies Harmful?

If your home is full of drain flies, you might be wondering what risks this infestation brings. Unlike horse flies and other parasitic insects, drain flies are not known to bite humans or animals. But that doesn’t mean they can’t be harmful. 

How To Get Rid of Drain Flies

Whether you’re dealing with drain flies in a commercial or residential space, in the kitchen or bathroom (or both!), you need to address a drain fly infestation quickly and safely.

The first step to eliminating drain flies is to remove their feeding and breeding grounds. Regularly clean and disinfect drains, remove any organic matter build-up, and use drain cleaners, bleach, or boiling water to help get rid of eggs and larvae before they mature.

To prevent the return of drain flies, address problems at the source: have pipes inspected to identify and eliminate blockages that prevent food, waste, and water from draining properly. If necessary, replace defective or damaged pipes and drains that leak and invest in drain covers and screens to prevent pests from entering in the first place.

After treating your drains for flies, don’t wait for them to return to take action. All treatment and preventive efforts should occur regularly. If you’re able, employ the services of pest control professionals to develop and execute a pest control program for you.