If you were a fly, where in my house would you be breeding?

[OakSun]

So get those annoying black house type flies, killing 1-2 a day. Where the fuck do they live/come from? New build, loft is sealed, the walls? Gaps in floorboards? (Hard flooring)

Inside the rotting carcass of the dead mouse/rat that's lurking somewhere in your home (probably under the floorboards/in the walls)? That was my experience at least. They looked like ordinary house flies but were quite 'dozy' and tended to aim for the window of the room they emerged in and lay on the windowsill in a prone position as if dead.

Have you checked kitchen cupboards for any opened packets of e.g. raisins, that might have been adopted as a breeding ground? Happened to me.

Do you have any plants? Ours seem to emerge from the soil (but they are little fruit type flies so may be different)

Look up loft flies

What kind of fly though?

Bluebottles hatch in rotton meat
Houseflies (the ones that circle the light) hatch in literal shit
The weeny ones, like fruit flies or knatts hatch in the likes of soil and drains.

Agree in a new build, that was probably being built in good weather they have lay eggs in the loft insulation and are hatching as perhaps the heating on etc, had this in my new build years ago

@TheGrandHighWitch

Inside the rotting carcass of the dead mouse/rat that's lurking somewhere in your home (probably under the floorboards/in the walls)? That was my experience at least. They looked like ordinary house flies but were quite 'dozy' and tended to aim for the window of the room they emerged in and lay on the windowsill in a prone position as if dead.

This... the maggots crawl under the floorboards and then hatch when the weather gets warmer . We get this once per year at least

Someone I know once had a fly infestation in the little space between the windows and the frames

Look up cluster flies, we get them

We had them in our loft when we moved in and got the house warmed up. It was a new build but had stood empty for a year. We got them coming through the window vents too.
Pest control came and put a smoke bomb thing in the loft which solved it.

In DPs House share when we first met his housemate cooked poptarts and stuff like that, I pulled out the crumb tray in the toaster and it was full of maggots

Could they be coming in through the bathroom extractor fan?

Dead bird trapped in sealed up fireplace for us, minging. Like something out of a horror film when i came down one morning, was literally sucking them out of the air with hoover.

inside the rotting carcass of the dead mouse/rat that's lurking somewhere in your home (probably under the floorboards/in the walls)? That was my experience at least. They looked like ordinary house flies but were quite 'dozy' and tended to aim for the window of the room they emerged in and lay on the windowsill in a prone position as if dead

You've been in our house! Accompanied by the disgusting sweet smell of rotting rodent carcasses.

Our pest control chap says it's too early in the year for cluster flies, and they are smaller than these dozy fat ones.

@TheGrandHighWitch

Inside the rotting carcass of the dead mouse/rat that's lurking somewhere in your home (probably under the floorboards/in the walls)? That was my experience at least. They looked like ordinary house flies but were quite 'dozy' and tended to aim for the window of the room they emerged in and lay on the windowsill in a prone position as if dead.

This! Except the not knowing if we have a rotting carcass somewhere, this describes them exactly. Only today did today’s dead on its back on the windowsill spring to life as I went to flick it out the window. They all seem to be upstairs mainly, but will check kitchen cupboards. Nope we do have them downstairs as well, one cheeky fucker decided to fly into the open fridge and die of shock of the cold.

If it's any consolation, they won't last too long...and they're easy to kill!

They'll only be there for a few days. Just keep killing them or get some indorex spray

Check the extractor fans in bathrooms