In North American Katydids, Green isn't the Dominant Colour, Pink is - Scientific American Blog Network

Recent breeding experiments have revealed that bright pink, not green, could be the most genetically dominant colouring of the North American oblong-winged katydid.

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Pink, yellow and orange katydids occur as a result of erythrism – a genetic mutation controlled by recessive genes that causes an absence of a normal pigment, such as green, and/or an excessive production of another pigment, such as red or pink. It made sense, seeing how rare pink, yellow and orange katydids are in the wild.