Can't Stand Those Black "Bees"

I don't know that they are bees. They sound like bees, although they over in place. We get them this time of year. They come out in the evening, just when it's cool enough for my evening walk. The hour before it's dark enough to call it dark, and even later up until it really is dark. They hover about 18 inches above the asphalt pavement on our quiet, country-like roads.

Once you get accustomed to looking for them, you can see them 30 feet ahead. Sometimes you can change course and not disturb them, except they usually seem disturbed and move—sometimes away from you and sometimes right at you, circling up near your head. In the past I used to swat at them; this year, the few times evening temperatures have been cool enough to walk, I've ignored them. Until last night.

I went out about 7:30 PM, a little earlier than usual. The temperature was still 90 deg F, but I decided to go earlier to get out and back before the black bees came out for their evening whatever-it-is-they-do-when-they-hover activity. I wasn't early enough, however. Just as soon as I got on Scalloway Circle I heard one, I think, but wasn't bothered by it as it moved off somewhere out of sight. On the next street, 600 feet of Scalloway Drive, I encountered no bees. On the next street, Sherlock Drive, I was attached. I heard one buzz near my head before I saw it. It buzzed me four or five times, circling and circling, retreating and advancing, usually staying out of sight. I couldn't stand that and swatted at it with my...handkerchief and my hands. I kept grabbing my collar in back and shaking my shirt, lest that pest light on my back and sting me. I must have walked out of its range, for it left me. On the return walk I was not accosted by any black bees, though at the same place I saw one leave its hover and fly away.

I say "bees", but what are they? They have a cigar shaped body, thin and maybe 2 inches long, and a wing span about the same length. They are all black so far as I can tell. They come out after the sun has set, but seem to disappear after dark; at least I never hear them on later walks. They hover 18 inches above the pavement, and seem to prefer lighter color pavement to darker. Scalloway Drive was just oiled a couple of weeks ago, and is very black. The other two streets were not oiled and are lighter asphalt. The "bees" seem to be on the lighter streets. I've seen as many as three of them hovering ahead of me on the street. They never fly off into the woods. The one tonight flew into a back yard, not the woods. They buzz like a bee; hover close to motionless like a hummingbird, and fly in a fairly straight path.

What are these things? I'd like to know. Possibly they don't sting at all and are just a nuisance I can blissfully ignore. Why do they just appear in late July and August? Are they out in the morning as well, in the lightening hours, or just the evenings? I never see them in the morning. I'm tired of them ruining a month of evening walks.