Flying ant?

In Salt Lake City; yard has zero grass; xeriscaped with native and other plants suitable for hot, dry climate.  Sorry, no photo.  Insect size approx. 1/4"; solid dark color; single winged; wings length of body; body three segments (head, mid, rear); look much like ants.  Unique habit: they swarm by the hundreds all along front of house; within 1"-6" from any surface... especially windows, rusted metal sun, and wooden furniture.  Rarely do any of them land.  They just continually buzz around the same areas ALL during daylight hours.  As the sunlight gradually ends they go away, I know not where, only to return the next day and continue the same habits. Don't bite; if one lands it's usually for only a second or two. 

Are these insects good to have around due to native plants?  Are they harmful in any way?  What to do if they are.  Thanks to anyone who knows the answer.