Seasonal and Age-related Changes in the Behaviour of the Genji Firefly, Luciola cruciata (Coleoptera, Lampyridae)

Seasonal and age-related changes in the nocturnal behaviour of the Genji firefly, Luciola cruciata, were studied along the Kiyotaki River in Kyoto City (western Japan) by recording the locations of the adults at capture and by individual marking. The proportions of males resting near the ground, resting on trees and flying were constant through the adult life, and roughly constant throughout the season. About three quarters of resting males were found on broad-leaved trees. Conversely, newly emerged females remained near the ground and copulated there soon after the emergence, but with an increase in age they gradually changed their resting sites from near the ground onto broad-leaved trees. Similarly, the proportion of females resting on trees increased with the advance of season. During the observation time (20 : 30-22 : 30) few females were flying. In the riverain habitat of adult L. cruciata, grasses are important as copulation sites for males and newly emerged females, and broad-leaved trees, where the risk of predation by spiders is believed to be low, are important as resting sites for males and older females.