The cuticle and viscera of Manduca sexta (L.) moths were colored by including Calco® oil red dye in the larval rearing medium. Male moths so reared, using dye concentrations as low as 0.05% (wt/v), produced spermatophores in which the red color could be detected with the naked eye when they were removed from females that had mated with the dye-marked males. Forty-nine biological stains and 5 food-coloring dyes were evaluated as sprays for marking the moth's body surface. Many were satisfactory.