Changes to ambient temperatures under climate change may detrimentally impact small ectotherms that rely on their environment for thermoregulation, however there is currently a limited understanding of larval thermoregulation. In this study we investigate the thermoregulatory capacity (buffering ability) of 14 species of day-flying Lepidoptera, whether this is influenced by body length or gregariousness, differs between adult and larval life stages, and what mechanisms are used; microclimate selection or behavioural thermoregulation. We found that Lepidoptera larvae differ in their buffering ability between species and body lengths. Gregariousness did not influence species buffering abilities. Larvae are worse at buffering air temperature than adults, and rely on different thermoregulatory mechanisms; adults rely on behavioural thermoregulation, and larvae rely on microclimate selection. This implies that larvae are dependent on the area around their foodplant for effective thermoregulation. These findings have implications for the management of land and species.

Climate change poses a severe threat to many taxa, with increased mean temperatures and frequency of extreme weather events predicted. Insects respond to non-optimal temperatures using behaviours or local microclimates to thermoregulate (thermal buffering ability), or through physiological tolerance. We studied the thermal buffering ability and thermal tolerance of a community of 54 butterfly species in Panama. Thermal buffering ability and tolerance were influenced by family, size, and colour, with Pieridae, large, and dark butterflies having the strongest thermal buffering ability, and with Hesperiidae, small, and dark butterflies tolerating the highest temperatures. We identified an interaction between thermal buffering ability and physiological tolerance, where species with stronger thermal buffering abilities had lower thermal tolerance, and vice versa. This interaction implies that most species will be vulnerable to climate change to an extent, considering that species appear to adapt to one strategy at the expense of the other.