I'm not sure this is of interest here as it's not the Sierra, but I'll take the chance it may be.
I spent 3 nights in the Trinity Alps (North Fork area - west of the high peaks) this past week. Most of the trip ranged from 3,000-5,000 ft elevation, with a couple parts up around 6,000. At the lower elevations the 'skeeters ranged from 0 - 1, maybe a 2 in a couple spots near water. They were a 2 while hiking higher up through Grizzly Meadow in the early evening.
There were some other flies around during the day throughout the region ... I'd say about a 1, sometimes slightly more.
There was an extremely persistent and angry hornet (well a large bee of some type) by the campsite at the top of the ridge near "Bob's Farm". Fortunately I wasn't planning to camp there, and this guy hastened my departure from that spot, as he clearly wasn't pleased by my presence.