Fig. 5. Temperature distributions on the forewing of six species of Eumaeini butterflies.
The temperature distributions were obtained by processing infrared flux images taken by a thermal camera with measured two-dimensional emissivity, transmissivity and reflectivity maps of the butterfly wings (Supplementary Fig. 36). The thermodynamic steady state was reached within 10 s of the exposure of the wings to the illumination due to their small thermal capacity (Supplementary Fig. 39). Within each sub-figure, the top shows photos of the dorsal and ventral forewing, and the bottom shows wing temperature distributions under four experimental conditions (i.e., light simulating full sun incident on the dorsal or ventral wing surface, and cryostat temperature Tc, of +20 °C or −40 °C). Tc = +20 °C simulates an environmental condition with a relatively high ambient temperature and humidity; Tc = −40 °C simulates an environmental condition with a relatively low ambient temperature and humidity. The exact combinations of ambient temperature and humidity simulated by Tc = +20 °C or −40 °C are provided in Supplementary Fig. 35. One individual per species was tested for this study.