Too many to count... In all honestly, i would guess well over a thousand bugs in the last 10 years.... one such encounter really sticks out in my mind:

Two or three years ago I was riding on a bike path next to a river, the sun had just gone down, and the bugs were coming out. I was near the end of the 26mile round trip, coasting down a slight hill, I had my mouth wide open, trying to catch my breath from climbing the other side of the hill. Next thing I know, im riding through what a thought was smoke from a campfire, then it felt like hundreds of pins hitting my face, arms, and legs, it wasn't smoke, it was millions of mosquitoes! By the time I figured this out, it was too late, i had a mouth full of the things, i took a swig of water from my camelbak and tried to spit them out, but to no avail, they stuck to everything in my mouth, my teeth, the roof of my mouth, my tongue... everything, plastered by these black little creatures from hell. I took another gulp of water, and tried to spit, i couldn't even get the water out of my mouth, the taste was horrible, I wanted to puke, but i couldn't, some unknown force made me swallow.

I thought i was out of the clear, i lived through the great bug cloud. that was, until i ran my tongue over the front of my teeth... bugs, everywhere, it was like sand paper... i used my tongue to scrape the rest of the bugs off my teeth, these i could spit out, all but a few on the back teeth, it was easier to just swallow them. It took me another 45 minuets to make it home after the encounter i was spitting out bugs the whole way. I must have spent another hour brushing my teeth, and flossing, a mosquitos can really get lodged between two teeth at 20mph.

Has anyone else come upon these clouds of bugs when riding? I have learned my lesson, dont ride with your mouth open!