What is this bug?!!

[Merrymeeting]

I wonder about this every year and have never been able to find an answer.

Every year about this time, these little bugs show up and annoy the h@ll out of you when you are out for a walk. They are little, gnat-sized, black bugs that swarm in front of your face. They don't land. They don't bite. They just fly in front of your face incessantly. I assume, like many bugs, they are attracted by the carbon dioxide. But other than being very annoying, they don't seem to serve any other function.

Anyone know what they are? I was able to catch one (see picture)