Abstract Black( bl), a new spontaneous mutation affecting eye color is described for Ephestia cautella. Results revealed that this mutation is a simple Mendelian sex-linked recessive with complete penetrance. The viability and reproductive potential of the black-eyed strain are not different from those of the wild type. Studies on the interaction between black and another sex-linked recessive mutation orange eye indicated that the two were not allelic as crossing over between them occurred. In some genotypes black appeared to be epistatic to orange, but in others interactions between these two mutants produced a red-eyed phenotype.