Re: Why so many spinner colors?
If your daytime fly pattern matched the natural, then logically, the changes in visible light would cause the pattern to continue to match well at dusk. The natural is not changing, after all.
Therefor, perhaps it is the large percentage increase in ultraviolet light that causes the sherry spinner to be more effective at dusk than the pink lady. What is your pattern for the two flies, that might give us some indication?