What type of small fly is this? (UK edition)
October 15, 2021 4:34 AM   Subscribe

I get a small cloud of flies in my flat, I'd like to identify them, but googling either points me to fruit flies (I think these are too big for fruit flies) or a load of 'common flies' that don't seem to fit.

They’re not the easiest to photograph but here’s a couple of attempts.

They’re not the regular type of fly that buzzes and flies into windows (I think those are house flies?). These are about 1cm long or a touch less, but narrow, about half the width of a house fly. They're completely silent, and fly aimlessly in a little cloud in the middle of my living room.

I live in Scotland, in a new build flat, by the sea, and they seem to come in when I open the external door, rather than being endemic to the flat. But then they remain. If I spray fly spray I can sometimes clear the flat of them, and they only reappear if I open the external door again, so I think they’re mostly coming in from outdoors rather than breeding in here. But I don’t want to spray more than I have to since I’m working from home and here pretty much round-the-clock. Most years I get them throughout the summer but this year they’ve only really appeared in the past few weeks as autumn set in.

I do have a much-loved fig plant which I think has fruit flies in the soil (fruit flies are the tiny ones that just look like black dots, right?). I have wondered if these might be fruit flies in a different stage of their life cycle, but I put one of these catchers in the pot this year. The catcher has lots of tiny flies on and I’ve not seen the tiny ones flying around anywhere else in the flat like I used to before I put the catcher out. I assume, then, that they’re being dealt with at source now and aren’t related to these ones, especially since these ones seem to come in through the open door from the outdoors.

I'm only about 100 yards from the sea, so wondered if they might be the kind of thing that lives on seaweed, though the coast near here is a stone sea wall, not a beach covered in seaweed.

I'd like to identify them partly out of curiosity about my silent, enigmatic flatmates, partly to help me try and get rid of them.
posted by penguin pie to Home & Garden (7 answers total)
They could well be cluster flies. Harmless, and common in more rural areas as the weather turns colder.
posted by pipeski at 4:46 AM on October 15, 2021 [1 favorite]

I was also going to guess cluster flies, which is what I’ve assumed some of our flies are. They fly around much more “lazily” than buzzy, frenetic house flies. No less annoying though.
posted by fabius at 4:51 AM on October 15, 2021

Not sure what they are, but I can confirm that they're definitely not fruit flies, which are much less than 1cm long and not that shape.
posted by ManyLeggedCreature at 5:59 AM on October 15, 2021

What you have in your Ficus are fungus gnats, and you can also get rid of them by watering it (much) less often. It will do fine with a quarterly soaking.
posted by SaltySalticid at 6:01 AM on October 15, 2021 [3 favorites]

Best answer: I think they are Lesser House Flies.
posted by essexjan at 6:56 AM on October 15, 2021 [1 favorite]

I have had them; I use a hand vacuum cleaner to capture them. You can release them or exterminate, as you see fit.
posted by theora55 at 7:46 AM on October 15, 2021

Response by poster: Thanks, all. I think essexjan has it with the lesser house fly, judging by the description on Wikipedia that it is "best known for its habit of entering buildings and flying in jagged patterns in the middle of a room".

Cluster flies was a good guess, but from what I can see in YouTube videos, they buzz, and are attracted to windows. These guys are silent and don't seem to have any particular interest in light sources.

The further wikipedia observation that "During short breaks and in the night hours, the flies sit on lamps or on walls and leave their small excrement marks" is fortunately not something I've noticed but has definitely encouraged me to keep trying to get rid of them, and their excrement-leaving ways. For which theora55's suggestion might come in handy, with a full-sized vacuum in my case...
posted by penguin pie at 10:23 AM on October 26, 2021

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