Little tiny flies causing trouble

Factual Questions
1

I’ve got a problem beyond my experience with flies!

I manage a retail store, (a small one, shop floor is about 25 feet by 20 feet), and in the last two winters we’ve been plagued by tiny little flies.

The seem to be just young versions of regular house flies, (I’m in the UK). I’ve searched around the shop for some old pile of food or rotten meat they’re hatching from, but can’t find anything. Plus they just turned up last winter and vanished over the summer, only to appear again this winter. Which seems backward for flies to me.

I’m currently using a nasty powerful fly spray four of five times a day to wipe them out. They gather in little clouds right over my counter so their in between my face and the customer’s face, like they know what they’re doing! After I wipe out one wave it takes about an hour or two for a new load to arrive. I’m sure it’s a differant wave because I have to wipe up the corpses after each blast.

Does anyone have any knowledge of fly behaviour that might explain this, or more importantly, how to stop the little [bleep]s ?

2

I just got rid of some flies by purging the drains. They were never seen around the drains, so we were spraying the air and walls, and eventually decided to put foaming Drano in the floor drain and they disappeared.
Of course that might not be your source. But you might also check nearby drains, especially those just outside your doors that may seldom get flushed out.

3

I agree with Pliny’s comments, essell. I work in a large retail food-service/grocery store and we have specific procedures for dealing with fruit/drain flies, which can be a real nuisance in our artisan bakery/food service areas. They appear precisely as you describe them–small clouds of minute flies hovering around and being a general bother. They can be knocked back with chemical treatments and meticulous housekeeping; especially food prep areas, drains, storage areas and the like. This link , although a commercial site, offers some useful tips. Hope this is helpful in your situation…