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Insects in Drains: Identification Guide to Drain Flies and Other Bugs Found in Drains (With Photos)


How to Identify and Control Insects and Bugs in Drains

This article helps you identify the insects that are in your household drains. Once you know the drain insect you are dealing with, you will know how to respond and control the problem.

Quick Guide to Insects Found in Drains


Phorid flies

Small black fies

Occur in swarms around drains

Moth or drain flies

Gray, furry, look like tiny moths

Often perch on walls near infested drains

Fruit flies

Small, brown, red eyes

Hover around fruit


Small, lithe, look like little fish

Nocturnal; sometimes found in sinks


Many legs, fast, brown

Found in basements and garages


Brown, wings, long legs

Nocturnal; can occur in drains


Phorid Flies

Phorid flies are little black flies that can multiply out of control in drains. The damp, unsanitary conditions of some drains, particularly those in basements and bathrooms, are ideal for little black phorid flies to establish a colony and start reproducing.

There are many kinds of phorid flies (family Phoridae), but that fact likely matters little to the homeowner who discovers a small swarm of the little black flies in their basement, bathroom, or home. The larvae – technically called maggots – live and feed in drains and pipes, so the best way to attack a phorid fly infestation is by cleaning up the environment that allowed the colony to get started in the first place.

Phorid flies, doing what phorid flies do.

Phorid flies, doing what phorid flies do.

Phorid Flies Are Not the Same as Fruit Flies

While both insects are small black flies and occur in colonies or swarms, these two insects are different. Fruit flies are lighter in color and have red eyes; their maggots often feed on fruit and other foodstuffs. Phorid flies, on the other hand, are black are feed on everything from decomposing animals to the gunk in your drains. Some phorid flies have interesting life cycles, and the smallest fly in the world is a phorid fly.

How to Control Phorid Flies in the Drain

There are a number of steps you can take to get rid of phorid flies. Sprays that contain Permethrin are effective, as are some kinds of "fly strips" that hang near the affected drain or area and attract and trap the flies. This video is a good place to start when looking for a way to control phorid flies:

Close-up of a moth fly, Family Psychodidae

Close-up of a moth fly, Family Psychodidae

Moth Flies

Moth flies are often simply called drain flies, because they almost always live and reproduce inside drains. Phorid flies (above) also occur in drains, but also in many other places and environments. Phorid flies in your house might be coming from several places; moth flies are almost certainly a sign that you have an infestation in one or more of your drains.

Called "moth flies" because they look and act like little gray moths, these insects (family Psychodidae) are harmless to humans are cannot bite or sting. They are annoying however, and when present in large numbers can be a sign that there is a seriously unsanitary situation in your bathroom or basement.

Like the Phoridae and all other flies, moth flies undergo complete metamorphosis that involves four stages: egg, larva, cocoon, and adult (this is the same as butterflies, beetles, and wasps). It's the moth fly larvae, called maggots, that feed in groups on the gunk inside your drains.

What to Do About Moth Flies or Drain Flies

Like phorid flies, moth flies (aka drain flies) need a good environment where they have food and protection. If there is a colony in one of your drains, there are several ways to deal with it, including simply spraying fly spray into the drain. If this direct method won't work (for example, it's a sink in a kitchen or bathroom and too close to humans to use fly spray), there are several other good methods to try to get your drains fly free. This good video offers some other ideas:

Fruit Flies

Fruit flies are a very common pest, especially in kitchens near bowls of fruit (they really like bananas, especially overripe ones). Like phorid and drain flies, fruit flies are harmless and can't bite or sting. But like those other groups, fruit flies can be unbelievably annoying as they hover around you.

Fruit flies have been known to take up residence in drains, but it's more likely that the little flies you're seeing around your basement or bathroom are phorid or moth flies. Take a close look at the little bugs and see if you can tell what color their eyes are. If the eyes are reddish or light brown, it's almost certain that you're looking at a fruit fly. And it's looking at you.

How to Get Rid of Fruit Flies

Since fruit flies eat fruit, your best bait for a fruit fly trap is a piece of banana (I have also used red wine, since they always seem to want to hover around and fly into my glass at the end of the day). This video shows you have to make a cheap and very effective fruit fly trap:




Silverfish, besides having a great name, are nothing more than harmless little bugs that you may see in your home from time to time. Even though they resemble a tiny prehistoric fish, they are in fact insects, just like the most beautiful butterfly. Silverfish live in the dark, dank corners of your home, including sometimes in drains. They want nothing more than to be left alone, venturing out at night to quietly gobble up the gross bits that settle into basement corners and drains.

Silverfish, along with centipedes and most spiders, are an essential part of your home's free nighttime cleaning service. You definitely want to leave them alone to do their thing.

House centipede

House centipede


Centipedes, along with the previously mentioned silverfish, are an important part of a home's maintenance team. They are hard to love, with multiple wiggly legs and a tendency to suddenly run out from under boxes in your basement or garage. I do not like centipedes, and I like almost everything that creeps and crawls. They are too fast and too leggy, even for me.

However, that doesn't change the fact that they are on our side. One of a centipede's favorite meals is – wait for it – cockroach eggs. If they will eat that, you can bet that they will eat every other gross thing that winds up in your basement. Who else is going to do that for you?

German cockroach

German cockroach


There are many, many kinds of cockroaches, nearly all of them living in the wild where the typical person never crosses their path. Unfortunately there are some members of the cockroach family (Blattidae) who basically ruin it for everyone else. These bad cockroaches are among the worst and most unsanitary pests in the world.

The German cockroach is the one that will sometimes come out of your drain. This insect has leathery wings, long legs, and a pre-flattened body, which makes them hard to catch and harder to kill. In addition, the rule of thumb, that if you see one roach you have dozens, is sadly true.

If you see even one cockroach, immediately call an exterminator. Do not mess around with home remedies and squashing. Meanwhile, check out this awesome movie clip:


This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.