Thermal profiles of Cicindelidia haemorrhagica (Coleoptera: Cicindelidae) activity in hot springs in Yellowstone National Park.

This article focuses on the thermal ecology of the wetsalts tiger beetle, *Cicindelidia haemorrhagica*, in Yellowstone National Park (YNP), specifically examining how adult beetles interact with substrate surface temperatures in two thermally active sites, Dragon Spring and Rabbit Creek. Using thermal videography and direct temperature measurements, the study found that adults spend the most time on surfaces with temperatures between 30 °C and 40 °C, with occasional brief exposures to substrates exceeding 50 °C, including a maximum recorded surface temperature of 61.2 °C at Rabbit Creek. The findings suggest that while *C. haemorrhagica* adults can tolerate high thermal environments influenced by geothermal activity, they do not remain long on the hottest surfaces and exhibit less behavioral thermoregulation compared to related populations, indicating possible physical adaptations to heat resistance. The study highlights differences in thermal profiles between the two sites and discusses potential structural mechanisms underlying the beetle's heat tolerance, though these remain to be fully elucidated.