Most of you know this, but I did not. There are a LOT of mosquitoes in Yosemite right now. I brought "natural" bug repellents and received 240 bites to my body. Bring both DEET based and PICARIDIN based repellents. I borrowed some DEET and it worked great...but it was already too late.
I encountered mosquitoes all day long. Every time we stopped walking, we were harassed, with the exception of when we were exposed to the wind.
There are a LOT of mosquitoes. Bring lots of repellent!
PS. The ineffective repellent I used was "All Terrain Herbal Armor Spray Insect Repellent". The repellent contained: Citronella Oil (10%), Soybean Oil (5.6%), Peppermint Oil (2.0%), Cedar Oil (1.5%), Lemongrass Oil (1.0%), Geranium Oil (0.05%). Those oils caused me to get a sunburn.
Link to REI product # 751171