Finally, a place without mosquitoes:
You're joking right?
Years ago in late summer, I and a friend hiked up (Yosemite Valley) from Bass Lake though the pass to the frozen lake at the top of Red Peaks and made camp. While were were there, a hiker came up from the other side and reported that he encountered someone who had not used enough repellant. He got bitten so many times he had an allergic reaction and had to be carried out by rangers.
When snow melts and forms pools, they become almost immediately infested with swarms of mosquitos. Sure, once you're above timberline, the numbers of mosquitos drops off, but the minute you drop below to where there is no night freezing, any path anywhere near standing water will have cloudes of mosquitos. Since nobody in their right minds makes camp in snow when there is bare ground a little lower in altitude, frozen conditions don't help much.
We took massive doses of B1 (which may or may not have helped), stayed away from standing water sources, rerouted around any swarms we blundered into and were covered head-to-toe in the strongest DEET cream repellant available from the second we crawled out of the bags. We had a very small number of bites after two weeks in Yosemite Valley. Most of the bites were on the tops of our heads, knuckles, ankles, elbows and the very few places we missed when we applied repellant.
NOTE: If one is bitten, I've been told that high heat applied to the bite site can neutralize the protein which causes the itching. Not high enough heat to blister, but just a little less than that is best( 'cause the heat has to penetrate through to the inner dermis, not just the surface).
