Re: Does blue excite the trout?
You said it before I could!
Blue light is more energetic, and attenuates less in water. It also refracts less than red or green light, meaning a more direct path. It is the most energetic portion of the visible spectrum that we and trout can see. On a dark winter day, the fish will see blue further off and brighter than other colors.
I started using blue lagartun wire on tiny nymphs last winter with much success. Similar to the blue poison tungsten. Blue and purple seem to be great attractor colors, but perhaps not the best when working a hole repeatedly over a few hours. I've also had good luck with the UV ice dubbings used as a collar. Just a touch of UV blue to get their attention.
Side note: Ever notice the bluish/green/purple sheen on a Brown trout's cheek? That kind of holographic spot over the gill flap. That's what got me started on putting some UV dub in as a collar.