John W. from Pittsburgh, PA on 8/28/2016 6:26:19 PM:
Mid September is a great time to ride the GAP/C&O! Warm days but not that mid summer stickyness. It's gets darker much sooner but it's also much cooler at night and a lot less traffic on the trails.
I've read that spraying on Off or Deet or some kind of bug spray will help. Stay out of thick vegetation and stick to the trail and open areas. I always like wearing long sleeve wicking shirts...less target area for insects to get on you. GAP is an old rail trail so it's wide and established gravel. C&O is a bit more "woodsy", wet, and muddy (if it's rained) and you'll likely see more mosquitos because of the still standing canal water. Ive never read on these forums about anyone contracting Lime disease after a trip on these two trails. I wouldn't be too concerned about it. Have fun.