Huge numbers of flies near nesting birds,please identify

[LondonB]

I live on the top floor of a tower block which which is a major nesting and perching site for many varieties of birds -pigeons,parakeets,starlings,gulls and occasionally a hawk.
There also vast numbers of these flies. I'd be very grateful if someone can give me any information on them;their life cycle,hosts,health issues re birds and humans. I am getting severely bitten,not by the adults but I believe by the younger form.They are 2-4mms in length.Thank in advance .

[Jason Green]

Hi London B, and welcome to WAB from a fellow Londoner!

No immediate ideas... they may be Vinegar flies from the Drosophilidae scientific family, though several different types breed in nests eating detritus matter, I believe without harming the young. Where did you find them exactly - in your flat, walkway, on the roof, etc.? I don't think they're a cause for concern so long as they don't become domestically invasive - then it would have to be in significant numbers, and even then...

Take care,

Jason

[LondonB]

Hi Jason, that was a quick reply ! I'm a West Londoner, follow the planes ! Even though it's late October,there are are huge billowing clouds of them outside my windows ,as dense as the midge clouds one finds in Scotland (IIth flr) .I do get them coming in and have ,without exaggerating, thousands of dead ones after I sprayed Raid on the inside of my windows.
Although they are interesting to look at ,there are maybe upwards of 300 birds who visit regularly or actually live on the roof .
I've been having quite a serious problem with being bitten and have thought the flies might have something to do with it. There was a bird nest in an air vent that was open to the inside of my flat. I there's any info re birdmites here ,I'd appreciate you pointing me in the right direction.
There was a beehive on the 9th floor which was pretty impressive ,I'll post those images in time.
Thanks for the welcome , LB