Once every year, or about that, I see a swarm of flying insects above my driveway. They are in the exact place every year, as if a magnitic homing. They look sort of like mosquitos but I don't think they are. They keep falling on to the driveway until it is covered by them lying dead or dying. I can only imagine they are mating and the male dies but it's only a guess. Later in the day they are all gone, I assume eaten by birds, or else they revivied and flew away. Any answers to this odd thing of nature?

Odds are they are the small flies commonly called mayflies. Yes, that does sound like a mating flight. The driveway is such a good spot because sunshine heats it and it provides thermal air currents for them to ride, so they can concentrate on breeding.

Sounds quite logical but why do they die? Thanks

richka : Sounds quite logical but why do they die? Thanks

They die after mating (or during the mating flight if they don't breed) because that's their only function as adults. The larvae do all the eating and growing.

richka : Sounds quite logical but why do they die?. Thanx

They die after mating (or during the mating flight if they don't breed) because that's their only function as adults. The larvae do all the eating and growing.

You gave me great answers to my question about what you called Mayflies. I looked up more information on Wikipedia about these insects and it said they gather around water, like Lake Erie for example, plus ponds, rivers, etc.
What you said all makes sense and about being above my driveway where the heat gathers. However, I live in Tucson, Arizona, a desert city. There are no lakes here. Rivers yes, but dry.
Could it be that just recently we have had lots of rain due to our monsoon season? Also, about a couple miles away there is an artificial lake. Some blue cranes live there and some ducks. Could it be they travel from there to my driveway? There are plenty of other driveways here, so why pick mine?
I think I asked you once before about crawling bugs in my back yard that you named Sow bugs. Last summer they disappeared and were replaced by cockroaches, only outdoor ones thank goodness. I wonder if the sows killed off the roaches. Anyway, this past summer there were neither sow bugs or cockroaches or any other kinds of bugs and I wondered why. Then it occurred to me it may be because I didn't feed seeds to the many doves here, which they always looked forward to in the morning. Could it be that the doves pooped while eating the seeds and that's what drew the roaches?
Thanks for any answers.
Richka

Non-biting midges (also known as chironomids) behave in the manner you describe and look like mosquitos. They are aquatic and could be breeding in the artificial lake. They emerge synchronously and form swarms, called leks, that are essentially nightclubs for mating midges.
Midges and Crane Flies, HYG-2129-97 (http://ohioline.osu.edu/hyg-fact/2000/2129.html)
Non-Biting Midges - ENT/rsc-15 (http://www.ces.ncsu.edu/depts/ent/notes/Urban/midges.htm)
non-biting midges - Google Images (http://images.google.com/images?source=ig&hl=en&rlz=&q=non-biting%20midges&um=1&ie=UTF-8&sa=N&tab=wi)

Thanks. Very interesting!