When two genotypes produce the same phenotype due to different environments, one is called the phenocopy of the other, because they differ genotypically. For instance, in Drosophila melanogaster, normal body colour is brown and hereditary variant has yellow colour. It was observed that brown and yellow flies reproduce sincerely, irrespective of changes in the environment, because the genotypes differ in the two cases. Cases are however, known where normal larvae, when raised on food containing silver salts, develop into normal flies. This is a phenocopy of yellow mutant, but would give rise to brown flies in the normal environment.