Phase Polymorphism in the Grasshopper Melanoplus differentialis

Abstract

Individuals of Melanoplus differentialis raised in isolation or in a crowded environment show conspicuous morphological differences indicating phase polymorphism. Isolated nymphs are pale brown at low humidities and green at high; crowded ones show extensive black pigmentation. Isolated adults are larger than crowded, while crowded adults show maturational color changes that are not present in the isolated. No behavioral differences have been noted in the one generation.