Q. My Scout Troop took a four-day backpacking trip in the Sierra Nevada mountains. The mosquitoes were the biggest problem on the trip. I used several different bug sprays, and only one of them worked. But the one that worked only worked for about 15 minutes. What type of bug spray (preferably natural) could I use that would keep the mosquitoes away for at least an hour? Also, I’ve heard that there is clothing that keeps bugs away. How effective is this clothing?