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Ask A Pro: Identification of Black Flies w/ Treatment Options

Camille Landry posted this on Jun 2, 2017

In this edition of Ask a Pro, a customer contacts us about some problematic flies that have set up shop in his home:


Good Afternoon,

We are finding these tiny black flies in our basement... they resemble fruit flys but have zero interest in any fruit fly traps or food/vinegar & water/ basically anything that fruit flys like. So I did some research online about drain flies and coming up through pipes in the house/ basement drains. And in some cases they resemble fruit flies. After trying the bleach, drain-o, arm and hammer, and any other web trick under the sun to get rid of the little guys ; I stumbled upon your product. Ordered and watched a couple video's about the product. We are on day 4 of using the product and we are still having issues. The numbers haven't let up, and I've scrubbed all the drains, manually taken off all pee-traps and applied the product at night to let it truly take effect. And they are still coming full force. Your product has great reviews and I've followed the instructions to a T... still no luck, they keep coming back. Would you have any kind of idea of what kind of pest we are dealing with and a solution to get rid of the larva ? There are no signs of water damage and the basement has never had a issue with flooding. They are mainly found by on the wall & in basement windows near the main water drain which is in the basement floor (no sign of leaking)... they are also in laundry room (also in basement but in a separate room) mainly by the windows as well... any assistance in this matter would be greatly appreciated.

I hope you hear from you soon. Thank you.

Travis C.

black flies

Solutions Response:

These are cluster flies, It is not advisable to use an insecticide within structures after the flies have gained access to the wall voids or attic areas. Although insecticidal dust treatments to these voids may kill thousands of flies, there is the possibility that carpet beetles will feed on the dead insects and subsequently attack woolens, stored dry goods or other natural products in the home. I usually recommend using a vacuum cleaner to simply suck them up.  You will need to try and locate the entry point.

Although aerosol-type pyrethrum foggers will kill cluster flies that have amassed in attic areas, it will not prevent flies from emerging from wall voids. For this reason use of these materials is not considered a good solution to long-term management of the problem.  Might want to spray the exterior southern side of the home next fall when temps start dropping.
Let me know if I can assist you any further,
Camille Landry
Categories: Ask A Pro
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