Colour in insect thermoregulation: Empirical and theoretical tests in the colour-changing grasshopper, Kosciuscola tristis

Body colours can result in different internal body temperatures, but evidence for the biological significance of colour-induced temperature differences is inconsistent. We investigated the relationship between body colour and temperature in a model insect species that rapidly changes colour. We used an empirical approach and constructed a heat budget model to quantify whether a colour change from black to turquoise has a role in thermoregulation for the chameleon grasshopper (Kosciuscola tristis). Our study shows that colour change in K. tristis provides relatively small temperature differences that vary greatly with wind speed (0.55 °C at ms^-1 to 0.05 °C at 10 ms^-1). The biological significance of this difference is unclear and we discuss the requirement for more studies that directly test hypotheses regarding the fitness effects of colour in manipulating body temperature.