flies 'pond skating' over paving?
 

hi all,

first post and looking for help.

we had part of our rear garden paved last year, and this year we have an abundance of small files which fly around the surface of the paving in large numbers. they're not afraid to enter the house so we're unable to leave any of the back doors open.

the garden is northeast england, east facing and partially shaded by overhanging trees.

any help in identifying these and convincing them to leave would be much appreciated!

many thanks
crowhall