Ladyofthewoods - I think all we can do about black flies (or mosquitoes or ticks) is take the normal precautions - and to TRY to maintain the right mental space. Like Danger Dave says, bad stuff is part of the AT experience and we have to have patience and fortitude or it will ruin our experience. Easier said than done, as I well know from experience! For me, the most important piece of gear (bug-wise) is a head net. It's the buzzing around my face that will make me crazy. I treated my head net (and a lot of other gear) to permethrin yesterday - hope that keeps the little devils from dive bombing my face! The bottom line is - hiking in the spring and early summer (pretty much everywhere, not just Maine) means TONS of bugs.