Re: Why so many spinner colors?
You are correct. I'm glad you mentioned Lafontaine's underwater observations on fly color.
Unfortunately, Pg 206, which discusses the orange and red spectrum of dawn and dusk are not shown.
An important point regarding the color of wings is made at the bottom of page 201; that on down wing flies, the wing color filters the light so the color of the wings "creates an aura of color around the body". For spinners with translucent or white down wings during daylight, this would be white and the color of the spinner body would be important. Hence the importance of having the correct body color for the pink lady spinner for trout feeding on them during daylight.
Applying this same logic to the aura around the body at dusk, the aura would be "sherry" or reddish orange, and this explains the attraction of the trout to a sherry spinner.
"Discovery consists of seeing what everybody has seen and thinking what nobody has thought"..........Szent-Gyorgy