Name that Bug

[4 for Boating]

So over the past week or so, there has been an increase of flying bugs.
Look a bit like mosquitos (not strong flyers) but are not and do not bite - sort of hover around in packs - hundreds of them. More of a nuisance that attacking.

What are these?
Are they an indicator of when the Black Flies will show up or another flying insect that will have a particularly strong year?