ABSTRACT
Insect mimicry and homochromy in relation to plants When I was in Thailand in the 1970s looking at the cabbages cultivated around Bangkok, I was fascinated by the extraordinary variation of color of the caterpillars of the moth Spodoptera litoralis (Noctuidae). The general color was light or dark green, but also yellow, reddish, brown, and very dark. According to my Thai colleagues, that was probably genetic. Others believed in mimetism, but really no one knew the cause of that variation. Recently, a paper has been written about the color morphs of the caterpillars of Eumorpha fasciata (Lepidoptera: Sphingidae) (Fink, 1995), which can be pink, yellow, green, or multicolored. The caterpillar feeds on various plants, and the foodplant quality seems to be a factor affecting larval color in that case. Foodplant effects on larval coloration may be widespread in the Sphingidae family, but most reports are such as for Spodoptera — anecdotal. Spodoptera litoralis feeds only on cabbage and the food-plant quality does not seem to be involved. This color variation is still unexplained but homochromy does not seem to be involved.
