I was reading up on Picaridin, and according to Sawyer (a company that manufactures both DEET-based and Picaridin-based insect repellents) Picaridin is more effective in repelling biting flies than DEET.
Sawyer.com: Sawyer Premium Insect Repellent (20% Picaridin)
For locations in the Sierra (and elsewhere) where biting flies are a big problem, it might be worth a try to use a Picaridin-based insect repellant instead of a DEET one.
Edited 1 time(s). Last edit at 08/11/2011 01:19AM by plawrence.