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Psychodid flies


bathroom flies (maybe) in the past month or so i have found hundreds and hundreds of flies that through research seem to be bathroom flies they are a 1/4 inch or smaller all black and heart shaped. they are all along my siding on my house. we live in a very low area in Illinois and always seem to have stagnant water in the yard and under the house. i don't know how to treat this. everything i have found on the Internet is about if they are in the house in drains. that is not my problem as of yet. i have noticed them getting in the house when the doors get opened. any help would be greatly appreciated.


Within my answers to previous questions, I have answered such descriptions such as yours. It sounds as if you are describing Psychodid flies. These flies may be found where there is chronic dampness in organic material. Within sewers this species breeds well in slime mold, but it is not restricted to that environment. You should be seeing tiny worm-like creatures wiggling in the medium, if that material is truly the breeding source. More likely, there is a downspout line entering an open clay or plastic sewer opening where these flies are emerging from. They would line up along a humid side of the building, close to the point of emergence from the sewer. You may also have an open drain near this landing area. Give me more information based on what I have written to you, or, look at previous answers. You can search for them on this site.

Best regards,

George Manning
Consulting Entomologist


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