Diversity in insect pigmentation, encompassing a wide range of colors and spatial patterns, is among the most noticeable features distinguishing species, individuals, and body regions within individuals. In holometabolous species, a significant portion of such diversity can be attributed to the melanin synthesis genes, but this has not been formally assessed in more basal insect lineages. Here we provide a comprehensive analysis of how a set of melanin genes (ebony, black, aaNAT, yellow, and tan) contributes to the pigmentation pattern in a hemipteran, Oncopeltus fasciatus. For all five genes, RNA interference depletion caused alteration of black patterning in a region-specific fashion. Furthermore, the presence of distinct nonblack regions in forewings and hindwings coincides with the expression of ebony and aaNAT in these appendages. These findings suggest that the region-specific phenotypes arise from regional employment of various combinations of the melanin genes. Based on this insight, we suggest that melanin genes are used in two distinct ways: a "painting" mode, using predominantly melanin-promoting factors in areas that generally lack black coloration, and, alternatively, an "erasing" mode, using mainly melanin-suppressing factors in regions where black is the dominant pigment. Different combinations of these strategies may account for the vast diversity of melanin patterns observed in insects.KEYWORDS Oncopeltus fasciatus; insect pigmentation; melanin patterning; melanin-promoting factors; melanin suppressors P IGMENT patterns are among the most striking and variable features of insect morphology. An extraordinary diversity in coloration distinguishes species, populations within species, individuals within populations, and different body regions (Wittkopp and Beldade 2009). Most insights into the mechanisms underlying such diversity have come from studies on melanization in Drosophila (Wittkopp et al. 2003;Wittkopp and Beldade 2009). Melanization is the pigmentation process wherein precursors (catecholamines) are converted into pigment molecules that are incorporated into the cuticle (Wittkopp and Beldade 2009). These studies have helped to identify a network of melanin genes and their roles in body color patterning (Wright 1987;Wittkopp et al. 2003;Wittkopp and Beldade 2009). The core part of this proposed pathway is shown in Figure 1. The pathway begins with the conversion of tyrosine to dihydroxyphenylalanine (DOPA). DOPA can then be used in two different manners: to produce DOPA melanin (black) or to be converted to dopamine, another precursor of black melanin. In the conversions from DOPA/dopamine to black melanin, the yellow gene is thought to play an essential role in promoting these processes. However, it is still unclear whether yellow plays a role in producing DOPA melanin, dopamine melanin, or both (question marks in Figure 1). Alternatively, production of dopamine melanin can be suppressed by converting dopamine to N-b-alanyldopamine (NBAD) or N-acetyldopamine (NADA). The NBAD bran...