maybe yellow reflects UV light somehow because many bug see in UV light
This is the actual reason why they flock to yellow. Certain bees and other insects see a different color spectrum than the human eye sees. Instead of the usualy ROYGBIV wavelengths that we can only see, certain insects can see wavelengths with a higher frequency (UV rays), and thus enables them to find their food. As a result, they can't see most of our color spectrum (red, orange, YELLOW, green) but their eyes pick up the UV light and they zoom in checking to see if it's food.