Bicycling & Spring Insects

I believe that depending on where one resides in the world, insects are of varying degrees of nuisance. I have no doubt that here in the U.S., those in the south would laugh at the minimal size of our bugs in Colorado. We certainly don't have mosquitoes the size of birds (as I have heard from those in the south - though I have to believe there is some exaggeration on their part) - but we do seem to get more than our share of mosquitoes as spring turns to summer.

Image found here
Gnat, resting

One of the things I seem to forget each spring is the enormous amount of gnat-like insects that invade. While they tend to gather in large groups mostly near bodies of water (be that rivers, lakes, or other), I find myself riding through them frequently, and ending up with at least a few in my mouth or nose. When I try to breathe only through my nose, I end up sucking them in through the nostrils, and when I breathe through my mouth, I end up choking on them. I've also tried not breathing at all, but when I'm in a place with so many, holding my breath can only last so long, and I end up taking an even bigger breath and swallowing more.

Although we're quickly reaching the end of this season, and it's certainly not a number one concern, I keep wondering if there's some way around ending up with bugs in my teeth. The best way I have found is just to avoid bodies of water, especially early in the day, but that isn't always possible or realistic. Do you have a tip or trick for avoiding insects while riding, or some way of keeping them out of the breathing passageways?