Flight Muscle Dimorphism in Geotrupes laevistriatus (Geotrupidae : Coleoptera)

The flight ability of five populations of the dung beetle, Geotrupes laevistriatus, was examined. Beetles collected in Sapporo, Hokkaido, did not fly, whereas indirect evidence suggested that those collected in Yokohama, Honshu, flew under an experimental condition. There was no significant difference in wing size between Hokkaido and Honshu individuals. The beetles collected in Sapporo and Akkeshi, Hokkaido had no developed flight muscle, whereas all individuals collected in Honshu, Yokohama (Kanagawa), Shizuoka (Shizuoka), and Ritto (Shiga), had well developed flight muscle. Brief discussion is given on the adaptive significance of the observed flight muscle dimorphism of G. laevistriatus.