No, not Mosquito Ridge...it's the extension of Foresthill Road past China Wall OHV staging area. That's the canyon of the North Fork of the American River in the background.
I believe that Mosquito Ridge heads off to the south out of Foresthill towards French Meadows and ends up by Uncle Tom's Cabin on Wentworth Springs Road, if I'm not mistaken. If you've done that route, EQPlayer, I'd love to get some details, as I have not and would like to...
Here's another photo of the canyon from the road.