black fly repellent

About 10 years ago, somewhere in my mid-fifties,
I agreed to take a trip through the boundary waters
with a bunch of marathon bikers. On the way we
stopped at the little town of Ely, MN, and wandered
around a bit looking for a cold brew and I noticed
a lot more marathon biker types wandering around
in shorts and backpacks and many of them had little
scabs on them. I learned this was due to black
flie bites so I bought a couple of small bottles of
BF-100 manufactured by LJB Labs. This stuff worked
great when DEET would not. Also noticed it worked
on black flies but not mosquitos.

I'd like to find more of this stuff as I am down to my last
couple of dabs but have had no luck. I like to fly fish
Ontario and sometimes the black flies can be a bit
distracting. The little devils take meat when they bite.

Any suggestions?

Thanks

Buff