Pattern formation on lepidopteran wings consists of the genetic and cellular processes that control the patterned synthesis of specific pigments. The proposed investigations present an attempt to elucidate the mechanism involved in the patterned development of one of the three major pigments in the wing, melanin (which is the pigment that makes up all black portions of the pattern) in Precis coenia and Heliconius charitonia (Lepidoptera: Nymphalidae). The spatial patterns of protein synthesis during successive days in the developing wing correspond precisely to the subsequent patterns of pigment synthesis. Patterned synthesis of phenoloxidase thus presages the subsequent pattern of melanin synthesis. The aim of the proposed investigation is to develop molecular probes for the phenoloxidase gene. The cloned phenoloxidase probes will be used in subsequent studies on the role of the gene product in pigment pattern formation. The cloned gene will also be used in future investigations on the control of patterned enzyme expression.