Drain flies are not harmful. They are not parasitic, and the human body is an inhospitable environment for their larvae. That’s the good news. The bad: you might have an infestation of these insects.
Drain flies love the damp and dark spaces inside your kitchen and bathroom sinks. They feed on organic debris and multiply. But are they dangerous? Can drain flies lay eggs in humans? Can they make you sick?
Do They Lay Their Eggs in People?
No, drain flies (Psychodinae) do not lay eggs in humans. They are not parasitic, and the human body is an inhospitable environment for them. Their close relatives, sand flies, are not as friendly, but these are not going to be invading your home in most regions.
In the one case we reviewed from the NCBI, a young woman did suffer from myiasis, which is the infestation of human or animal tissues by dipterous fly larvae. This was traced to the Eristalis and Psychodatraced family of flies. There are however many different subfamilies, and those that typically infest drains in homes are not harmful in this manner.
In this particular case, predisposing factors also existed, including:
- Lower standard of living in a rural area
- Poor personal hygiene
- No running water
- Open water buckets and pre-existing infestation in the lavatory pit
With that said, people often notices bugs lurking around their home and may be concerned if they have the potential to be parasitic. A prime example: are drain flies capable of laying eggs inside human bodies.
This shouldn’t be a concern to you. Psychodinae, your common drain fly, have no interest in human hosts. While it’s true that they lay eggs in organic matter, the human body is inhospitable to these tiny flying insects.
Compare this to nastier species of Insecta and Diptera: botflies, blowflies and fleshflies.
So, Where Do Drain Flies Lay Eggs?
As we mentioned, female flies look for organic matter to lay their eggs. Drains accumulate mold, debris from food, hair, and sewage which makes them ideal. However, they have been known to infest sump pits, drain pans and other unscrupulous areas.
The debris is eaten and also used as an area to lay eggs so their offspring can thrive. If you have drain flies, it’s highly likely you have a drain that is clogged or dried out.
Are Drain Flies a Danger to Our Health?
Drain flies don’t target humans to reproduce, but do they pose any harm to humans in other ways?
In short, it depends.
The occasional drain fly won’t be a problem for most people. If you’re able to catch the problem before they begin to multiply and wreak havoc, even better!
The problem: these flies reproduce rapidly. Females can lay up to 200 eggs that hatch within 48 hours. They reach adulthood in several weeks. The larva can appear as worms in drains and on occasion, a toilet bowl.
Larva can turn into adults before you even notice the first drain flies lurking around your home.
The bugs themselves typically won’t make you sick just from lurking in your bathroom or basement. They also direct their focus to decaying matter, unlike phorid and fruit flies, so they won’t pursue your food per se.
That said, if they do land on your food, they can transfer bacteria and microbes. (Obviously, something lurking in a bathroom or pipes is not going to be clean.) It is necessary to be vigilant if you have an infestation in your kitchen or areas where food is stored.
Individuals with asthma may be particularly sensitive to the dead and dried up parts of adults flies. Bronchial asthma can be caused by inhaling the fragments and dust.
Drain Flies: Almost Harmless
Let’s summarize: can drain flies lay eggs in humans?
No. This type of fly does not look for human hosts. Females look for a buildup of matter in standing water. They also do not bite!
If you’re burdened by pesky drain flies, we want to help you. Check out our drain fly guide to learn what steps you can take to identify and treat these pests.