And yes, the trout are on to us........why else would they rise sporadically through dusk, and then once the sun exits the landscape and our eyesight with it, do they begin rising all over the place?!
They're setting us up, that's why.
Seriously, they have clandestine meetings behind a big, midstream boulder and every so often they send out a scout to rise in a random foam line once or twice, just to keep us hanging around. If we are lucky, we manage to make a good cast, get a good drift, and hook the bastard when it takes our offering. That trout damn well knows we are going to release him after we bring him to hand, so it's no big deal; he's taking one for the team, and they all have a big laugh behind the boulder right under our waders.
Then when it gets dark, they spread out and feed on the multitude of hatching and egg-laying insects drifting on the surface film, all the while knowing we can't see a thing!
I can hear their laughter now..................