By Sunbeam
West Midlands,
United Kingdom 
Infestation of tiny flies at allotment - help !!
On the leaves on my plum tree,gooseberry bush and a patch of nettles there’s been huge clouds of tiny flies if I spray them they’ve just moved to other plants - like black currant leaves. What are they and what should I do?
Any advice much appreciated
14 Sep, 2019
Answers
If you've mulched with compost recently it could be something that's drawn to that.
Whatever they are the cooling weather will do for them fairly soon anyway
15 Sep, 2019
Thank you very much. I’ll try to get a photo and post it
15 Sep, 2019
Don't spray them with anything nasty though?
15 Sep, 2019
Sounds like they are greenfly. At this time of year they are producing winged males and females so they can lay over wintering eggs.
any chance of a photo sunbeam.
15 Sep, 2019