I just returned from backpacking in the Mono Creek, Silver Divide, and upper Fish Creek areas July 30 thru Aug 4. Each year I backpack during periods of peak mosquitoes without being bitten or bothered much. We visited elevations from about 8k to 12k. Although there were some mosquitoes in all vegetated areas, they were in usual numbers for this time of year. Some shadowy lodgepole and meadow areas had usual dense numbers of mosquitoes especially in the evening while sunny open to breezes bedrock granite areas had none. Generally it is drier than usual for this time of summer, however seeps draining down from areas of late melted snows takes weeks to drain off and dry. So many less sunny aspects above 10k or areas along seep paths are still only now peaking with greenery and wildflowers that are likely to harbor the bloodsuckers.
The High Sierra at crest areas always have areas of melting snow through summer that keep some mosquitoes active until early frosts of September fully eliminate them. Except early and late in a day when breezes are slack, mosquitoes tend to avoid dry areas without water or vegetation. And even in vegetated areas, squeeters from mid morning thru mid afternoon tend to take a low profile hanging out on greenery waiting for victims passing by. Else in the air, our buddys the dragonflies and damselflies will make em dinner. All this occurs every summer and any experienced High Sierra visitor ought to easily be able to predict where and when mosquitoes will and won't be a nuisance. This seepy lush Mono Creek location is typical of those areas sure to have squeeter all the way thru August.
We were fully covered in impenatrable to probosci lightweight synthetics materials, wear safari caps with neck and ear drapes, carried head nets for evening and night use, and used 100% DEET on the remaining uncovered bare skin areas like face and hands. Note I sleep tentless in an OR Basic Bivy, and had to use a head net or zip the mosquito netting zipper up each night as there were always a few mosquitoes that would have wandered by over the night hours if I had simply slept in the open to the suckers.
In all, I don't think I was stuck by the suckers more than a few times during the whole week. On some days no bites at all although I always noticed some about here and there. They hate 100% DEET and simply land atop my clothing that bends their pokers frustratingly. And those few bites were only because I often didn't have any DEET at all on for much of the trip. In fact at 9k we spent much of one breezy afternoon in swim trunks without DEET, jumping into a major stream where it dropped through bedrock slabs with potholes and laying about unprotected on the sunny bedrock that was only a few hundred yards away from a meadow where squeets were thick. In fact we jumped in lake, pond, and stream waters each day of the trip without getting bit in the nekid process. I'm one that hates feeling grubby from trail dust, however taking regular dips also removes sweat chemicals that draw mosquitoes. Of course one doesn't do so in a stagnant pond at some lodgepole meadow.
David Senesac
http://www.davidsenesac.com