Abstract
This study examined the regression of male interflash intervals of Luciola cruciata on ambient air temperatures at five sites in central Japan. The result indicated a significant negative correlation between these two variables at any of the sites. The regression lines varied from site to site and, therefore, the five local populations were classified into three types; the fast-flash, slow-flash, and intermediate types. This classification was supported by molecular biological studies, but contradicted the results of previous ecological studies based on interflash intervals only. My result suggests that first the slow-flash type and then the intermediate type evolved from an ancestral fast-flash type. The geographic variation in flashes of this firefly may have arisen from shifts in the response of male flashes to ambient temperature.