Poor stocked trout- they get no respect! As a resident of eastern Ma, put and take is the name of the game for me.
I do know of one or two brooks with natives but besides being easier to catch than fresh off the truck rainbows, they can barely
bend a four weight. A [stocked] large brown which has survived more than one season in Walden is one of the hardest, most technically
demanding fish available to most of us. To catch one on a fly is a respectable accomplishment.
Oh, and to answer the question, it's not when do they learn to hit flies that matters, it's when do they learn NOT to hit flies that counts.