Black flies - help!

[emc]

hi - since Tuesday this week I've had a lot of fat black flies buzzing around my house (some have a little bit of shiny green on their backs) It is absolutely disgusting. Am killing around 15 per evening (they are mostly around in the evenings when I turn my lights on?) Have invested in fly spray and fly paper and it's working fine in that it's killing them but I want to know where the source - I know everyone is going to say there's something rotting, a dead carcass somewhere but there's no smell in my house/have looked everywhere for rotting mouse/rat, whatever. Could there be something rotting outside, the flies are hatching there then entering my house? How do they get in? No windows are open. I have to say the numbers are decreasing but they are still THERE. Any help/advice v much appreciated. Actually I think they're coming in near my front window actually and I noticed that when I turned my heating off they seemed to decrease. thanks

[Bellenden Belle]

Do you have a chimney breast?

As a student I went away for the holidays and came back to find a pigeon had died in the chimney breast. It was unimaginably awful.

[emc]

i do, but its not a working one....could that be it? not sure if chimney is blocked up or not

[KidKruger]

Dulwich DIY.

Fly paper, hung from light fitting or ceiling.

Fly holocaust.

Sorted.

[Tradesman32]

Something has definitely died. Black flies come after the maggot phase... Maybe in the gutter above a window?

[aquarius moon]

Do you mean blue bottles?

If so, they are attracted by smells but also hate to be trapped inside so if you open windows they'll make their escape.

If they are breeding indoors, there must be maggots somewhere. You'll have to turn the place upside down looking for something that's gone rotten. Unfortunately if it's something dead under floorboards/behind walls it just means waiting til they all fly away.

[Applespider]

Leave half a bottle of cider open in the room where they are. They are attracted to it, fall in and drown in the cider. I am sure it is just as cruel as flypaper but I like to think they are dying happier.

[DulwichFox]

I had one in my living room on returning from holiday.

Not your typical shiny backed blue bottle.

Just a very large black fly. 3 times the size of a house fly.

Opened window... they usually find their way out.

Found it dead the next morning.

Might well be more that died while I was away.

DulwichFox