Paul,
Believe it or not I use a flashlight, with white light. Used to use an expensive lightforce light but it died and wasn't worth the money. I'd have to look at the light I use now to tell you what it is but its just a good quality flashlight. When we hit them with the light we shine it above them and bring the beam down and that seems to make a difference. I would say about half run off but they usually come back and eventually get shot. Some don't seem to care at all. Its only 120 yards from the window to the pile but the red and green don't shine as bright and the critters seem to run from them just as often. With snow on the ground I often don't even shine the light, can usually see ok through the scope.