Abstract
The stink bug, Pyrrhocoris sibiricus, which is a ground-living seedfeeder, shows wing polymorphism. To define the wing form and investigate the relationship between body size and wing polymorphism, adults collected from natural habitats were measured for their body length and forewing and hindwing lengths. The coloration of the hindwing (blackish or semitransparent) and the distinctness of the hindwing venation (distinct or indistinct) were also checked for all individuals. Individuals with blackish hindwings had distinct (developed) wing venation and showed larger values of relative hindwing length (RHL), while those with semitransparent hindwings had indistinct (undeveloped) wing venation and showed smaller RHL values. Moreover, the RHL values of individuals with different colors did not overlap. In female adults, individuals with an RHL equal to or greater than 0.4 were defined as macropters and those with an RHL of less than 0.4 were defined as brachypters. In male adults, individuals with an RHL equal to or greater than 0.5 were defined as macropters and those with an RHL of less than 0.5 were defined as brachypters. Macropters had larger body sizes than brachypters in both sexes.
