Seasonal Polymorphism of the Adult Rice-plant Skipper, Parnara guttata guttata(Lepidoptera : Hesperiidae) and Its Control

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Larvae an pupae of Parnara guttata guttata were reared various temperature and photoperiodic conditions. The adult morphology varied manifoldly with temperature and photoperiodic conditins during larval period. Longer photoperiod induced paler wing coloration and smaller size but independent of each other. Tmperature exerted threefold effect : lower temperature inducing larger size, stronger melanization and more conspicuous silver spots on wings. higher density combined with shorter day seemed to equalize adult size. Because of such compricated control of morphological features, the polymorphism in this species seemed to have different implications, including its role in connection with migration, from well known seasonal forms in other Lepidoptera.