Wear light-colored, protective clothing. Loose-fitting, long-sleeve shirts and pants made of tightly woven fabrics are best. Zippers beat buttons. Tuck in wherever possible and seal with duct tape if necessary. Finally, wear a head net.
Avoid floral-scented soaps, hair sprays, and deodorants. Biters home in on such smells, as well as sweat, body heat, and carbon dioxide. Pace yourself to avoid breathing too hard, and wear venting clothing to keep perspiration to a minimum.
Be choosy about your campsites. "Mosquitoes tend to concentrate in very isolated areas, especially around marshes and in the deep woods where depressions collect melted snow," says Bruce Eldridge, director of the University of California Mosquito Research Project. Blackfly populations, too, are greater in the vicinity of water—especially near pristine, fast-moving streams. Solution? Whenever possible, stay out of the shadows and steer toward windy areas like ridges and mountaintops. And when you pitch your tent, pick your perch carefully. "Try to camp where it’s dry," says entomologist Terry Whitworth. "If you’re right next to their breeding grounds, it’s gonna be bad."
Build a low-impact campfire if regulations allow. The smoke tends to discourage biters.
Talk to the locals before you go. Biter populations are so variable it only makes sense to chat it up with those in the know. Try hunting and fishing stores, guides and outfitters, and chambers of commerce. In areas where blackflies and mosquitoes can be really heinous (northern latitudes in particular for blackflies), the locals watch the hatch patterns very carefully and often know just where to go to avoid the current crop.
Calm the itch if the biting buggers still manage to get to you. We’ve heard of two multipurpose remedies for use in the field: Make a paste of baking soda and water, then dab it on the bite; or, rub on a bit of Preparation H ointment.