I don't know if anyone knows the answer definitively or not...
Supposedly people use red or blue lights at night b/c snakes can supposedly not see those ends of the spectrum.
Snakes (except some vine snakes) don't see like we see. I like to think of it like "Predator II" when the alien has to switch from infrared site to other sight types. They detect movement, they don't "see" a mouse as a mouse, but rather something warm, that smells like food that's moving. The vines snakes are an exception, they can visually recognize stationary prey.
Rome did not build a great empire by having meetings, they did it by killing all who opposed them.