As a follow-up to the review by PhLo S just below...my group went August 10-12. There were some flies and mosquitoes at the lower elevations, but nothing close to plague-level. As a precaution we wore long sleeve shirts and long pants, with the option to wear head nets. While hiking these precautions weren't really needed, but during rest stops the bugs can get annoying. The views at the upper elevations are amazing. This was one of the best hikes I have been on.