Fruit fly infestation

[LittleEsme]

Has anyone ever come across fruit flies in the walls of their renovation project?

The builder told me that, when removing the old felting and old roof, last Autumn, there were thousands and thousands of fruit flies swarming around. I had a peek and by the time I arrived, there were still loads but given the roof was gone, they seemed to disperse over the next day or so. Then came winter, problem solved.

Our new roof was completed last weeks and velux's and dormer windows are not fitted. I've just visited the site to measure and im gutted to see hundreds of the same
Specie of fly inside again. Bouncing off the new windows.

The house itself is 180 years old with stone walls over a foot thick. I waved my hand around to disperse the flies and a cloud seemed to
Fly out of the original stone.

I've had fruit flies around old fruit in my current home. They're a pain but once the fruit is cleared, they bugger off/die off.

I'm worried that, come completion, we'll have thousands of unwanted residents buzzing around before we even get settled in!

Has anyone ever experienced this?!

Are they definitely fruit flies and not something like fungus gnats? Seems odd therw would be fruit flies if there isn't any fruit. Fruit flies have red eyes and are a sort of orange colour. I think fungus gnats are black but you might have to Google them.

Thanks @Geneticsbunny. I'll have a Google now. They're definitely the same shape as fruit flies but I didn't click eye colour.

If there is standing water somewhere because of the renovations then that might be where they are hatching out from.

Thanks @Geneticsbunny
I think, on further googling, that they're Phorid flies.

I can't fathom it. No standing water nearby and they seem to be coming from the stone walls that have been hacked at (old plaster hacked off). The house has been exposed and roofless through the autumn and winter, so could it be the damp?!

They sound like cluster flies? Especially if they are appearing again with the sunnier weather?

Yes definitely sound like cluster flies to me.

Excuse my epic name change fail

Cluster flies are too big. These are exactly the same size as fruit flies.

I just want them to go!!

We had fungus gnats once in our kitchen, maybe these? Think they came in with a potted hyacinth, as they can live in soil/roots etc. Binned the plant, bleached the sink and overflow, sprayed bug spray every night for a few nights, got rid in about a week. They like the grot in plugholes etc, so yes they might be in soil/dirt in old stone wall.