Hosmer Lake is good this Fall and I always like it there in October, especially as a Brook Trout fishery. It is hard to beat an Olive Chironomid or Red Ice Cream Cone now. Scuds, Water Boatman, Leeches, Damsel Nymphs and Callibaetis Nymphs are all good too, and consider fishing them mostly on an NZ Wool Indicator, or Bung for sensitive eats.
Callibaetis hatches are not totally over so look for enough of them to create some opportunities for emergers and dries mid-day. Beetles and Ants are good, especially along the reeds.
A Ghost Tip or Emerger Tip (3 to 5 feet of clear sink tip) is a good line for Hosmer, and a Hover or Camo Intermediate is another deeper approach for leeches and scuds. Also, an Olive Zonker is a good one to strip, the Brookies are aggressive pre spawn and will attack that fly. Tuck a Micky Finn in the box too. And with the sinking lines give a Blob a whirl. It can be a good one here.