Sudden infestation of houseflies in apartment

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Sudden infestation of houseflies in apartment

I woke up one morning and there were 10-15 house flies hanging out on the ceiling and walls of my dining room. There were 20+ more in the window, behind the blinds. There are no holes or cracks in the windows or doors. I've also checked all the window screens and they are intact and fully attached. Also, there are no flies between the window and the screen, only inside. We don't leave food out, the trash is empty and there are no flies in any other room, other that when they fly there to escape the fly swatter. Still, they come back to the ceiling and walls of the dining room. Every time we think we've killed them all, 10 more appear but we can't find where they are coming from. Maintenance came out and scratched their heads but gave no solution. The only notable smell was a strong acetone-like odor the day before the flies appeared. The next day the smell was faint in the morning and gone by afternoon. It is now day 3 and we are hand vacumming about 20 flies per hour. HELP!!

Status: Open Jun 24, 2026 - 06:37 PM

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Staff Answer

RonDawson

Jun 25, 2026 - 11:44 AM

Typically when houseflies suddenly appear in an apartment its because something happened to cause it. Dead animals such as birds, rats, squirrels, etc in attics, walls and other hidden places may not be noticeable because the odor may be be drawn outdoors through vents, screens, etc. Other times trash containing meats, diapers, and anything that can rot has not been emptied in several days. Trash cans indoors and also outdoor recepticles can be the issue. Treatment using specific products for flying insects and flies such as CB80 can kill exposed flies. Here is a link to an infographic that will help - https://www.epestcontrol.com/content/...

Source: https://www.epestcontrol.com/content/...

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