A couple quick points about color because several posts here show a bit of a misunderstanding ... UV light is a wave length outside the visual range of most humans. The wave length is too long for us to see it. When a black light is turned on we see the tiny visual spectrum parts of its output, but not its primary output.

When that UV light hits a fluorescent material it refracts the light waves in a shorter wave length. Most materials reflect it as the same wave length or refract it to a longer wave length. Very, very few actually fluoresce with a shorter wave length...

UV light is a good thing for flies because it penetrates water farther than any color in the visible spectrum. Many fish can see UV which is outside our visible spectrum.

When colors fluoresce under UV (blacklight) they show what happens when a fly is reached only with UV... It refracts the mostly invisble UV as a shorter, and now visible wavelength.

So the light is carried to depth invisibly and then converted to a color fish can see at much greater depth...

Hope this helps...
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