Thoracic temperatures of Lestes sponsa (Hansemann) perching in sunflecks in deciduous forests of the cool temperate zone of Japan (Zygoptera: Lestidae)

Thoracic temperatures (Tlh) were monitored while the insects were perching. Mean T,h was about 28°C in both sexes perching in sunflecks. T,h was positively correlated with ambient temperature (TA) in both sexes. The radiant heat load, which was termed the radiation temperature (TR), in sunflecks ranged from 27°C to 50°C. TIh was regulated against TR. After capture 1 live and 1 dead 6 were taped with spread wings onto brown paper. The pair was put in a sunlit point of a sunfleck to measure T,h. Tlh of perpendicular males, to direct sunlight, was kept lower than TR under a high radiation temperature of more than 35°C. Tth of live males was usually kept higher than that of dead ones. The role of perching in sunflecks is discussed with regard to thermoregulation in this sp.