OP,
In between Abol Bridge and Hurd Brook can be nasty. Shady and swampy. Do not stay at Hurd Brook. Camp at Abol and blow through Hurd the next morning. Rainbow Lake campsite or Rainbow stream is good and light on the bugs. Faster moving water and larger bodies of water seem to not hold the bugs. Smaller bodies, swamps and brooks seem to hold the bugs. My hammock has a built in net so I don't worry about bugs at night. As you work south stay out of the high grass and weeds, don't sleep in fields etc. so to avoid the ticks. Out of all ticks should worry you the most. No poisonous snakes or spiders in Maine or NH. The Wolf Spiders do get big though. Had one repelling from my beard one morning and it scared the heck out of a NOBO.
I use lemongrass soap and oils along with an essential oil mix my wife makes. I also take vitamin b complex but have not done the apple cider pills yet. A dab or two on the neck and arms and I am good. Deer flies are the worse of all the bugs. They go after the back of the neck and hands. I clap my hands above my head when I am being harassed by a deer fly and usually kill it in a couple claps. I personally do not treat my gear or clothing with chemicals and never have. I grew up on the AT in PA and ticks have always been bad and still wont use chemicals. I really don't care what the chemical is I just refuse. Use chemicals if you want but I and many others have great success with a more natural approach.