Fly Size

[cje04]

I have two related questions that I've been wondering about lately and would appreciate any thoughts on.
1. Why do smaller flies (16-20) seem to be more productive in heavily fished waters, even when larger (12-14) naturals are frequent?
2. Why do smaller flies work better in stillwaters as the season approaches fall, as opposed to the larger flies of spring working year round?

[cje04]

No thoughts?

[Lewiskm3]

Perhaps the smaller flies can hide the slight discrepancies (profile, color, shape) that exists between the naturals and what we tie. As the fish in the pounded water have all seen the flies before, they might notice the larger flaws easier. Or perhaps the smaller they the safer they seem and the less they eye them before they bite them.

I would guess that when spring rolls around the fish are hungry after a long winter, and are willing to pound anything that appears to be a substantial meal, while in the fall they've wisened up a bit, leading to fish with a more selective feeding pattern, looking for stuff that more closely resembles natural food. I might be spewing bull crap out my typing fingers, but that's what I would assume.