In nature, firefly flashes range from green to yellow:
Results of our newly published study suggest that early evening-active species that signal in forested environments evolved yellow flashes because yellow shows up better against green ambient light (the “contrast hypothesis”).
Hall, D.W., Sander, S.E., Pallansch, J.C. and Stanger‐Hall, K.F., 2016. The evolution of adult light emission color in North American fireflies. Evolution,70(9), 2033-2048.