Drain flies not from a drain, or food flies not from food?

[samarrange]

We have a load of annoying small flies in our kitchen. They are small and black, about 3mm long. They look very like drain flies, which we had a few years ago in the bathroom, but we sealed up the sink overnight (plug pushed firmly in and duct tape covering the overflow) and they were still out in force this morning.

We occasionally get food flies in some or other opened dry goods in the cupboard, but they are usually larger, slower, and more "dusty" when you zap them (a bit like moths) than these little buggers. We have moved all of the opened packets out of the kitchen cupboards to another room and the flies haven't followed so far.

Any other ideas where to look for the source? The windows are generally closed.

Dragon flies have nothing to do with dragons.
Apparently.
😉😁😁

are they flying ants by any chance? can you link to a picture of something similar.

suggestions are:

some rotting fruit or veg or food somewhere you've forgotten - like a half eaten sandwich left in a carrier bag on the way home from work with some other things in you've not unpacked.

something rotting dropped down the back of a bin or rolled under a kick board

if you have air vents, something may have died or brought in something to the air vent.

if they are in the kitchen there will be some food source there where they are replicating

Potplants. A dose of nematode worms may be in order.

Not flying ants, and there's nowhere obvious for dropped food to be hiding... but I'm wondering what might be in the vent from the boiler to the outside. Will see if we can take it off for a look. Thanks for the ideas.

Yes if you have houseplants these are probably fungus gnats

No houseplants, and the insects we have don't look like fungus gnats (the legs are too short). On the other hand they don't look like drain flies either, at least not the drain flies on Google, or like fruit flies, so I apologise for the misleading thread title.

Someone mentioned flying ants. They are black like ants, but much smaller and quicker (flying ants are a bit dopey in my experience), and the body is not segmented.

@samarrange have you googled for what they are? can you post a link to some similar images?

They look quite a bit like the ones in this thread: www.mumsnet.com/talk/housekeeping/4774205-tiny-black-flies-all-over-house-help

I managed to catch one of the little buggers. Length about 2mm, wingspan about 4mm.

Also, we have noticed that first thing in the morning they are often to be found in large numbers on a slightly damp dishcloth, even an almost-new one that has only been used to wash up once. Presumably they are detecting nutritious bacteria or micro food particles on that.