Both laboratory-reared and field-collected pupae of the pine butterfly, Neophasia menapia F. and F., exhibited varying degrees of dark pigmentation. Most of the pupae, however, lacked this characteristic. Pupal coloration was not due to sexual differences, parasitism, or the quantity of food available during development. Although light was necessary for pigment formation, the effect was nullified by providing light-green foliage or a white background for the larva on which to pupate. Dark-green foliage of the previous growth year had an intermediate effect. Larvae that pupated on twigs or against a black background developed heavy pigmentation.