What are those flocks of flying bugs that just kind of sit over the sidewalk?

Question

Whenever it's summer and hot outside, there are annoying packs of flies around the sidewalks. They get on my nerves and was just wondering what they were.

Answer 1

Can't get a better answer than from an expert.  But I have a follow up question:  How does one get rid of them?

Answer 2

Many of the hordes of flies you refer to are midges or gnats that form breeding swarms.  The males and females get together in those swarms in order to breed.  Usually it is near water or moist areas, but not always.