Heatwave predicts a shady future for insects: impacts of an extreme weather event on a chalk grassland in Bedfordshire, UK

Climate change is set to become one of the leading causes of biodiversity loss worldwide, with extreme weather events projected to increase in frequency. Ectothermic animals such as insects are at particular risk, especially when they are isolated and unable to move through the landscape to track suitable climate. To protect such taxa, it is important to understand how they are impacted by extreme weather events and whether management could provide effective microclimate refuges. However, potential management interventions remain untested for many species. Here, we show that the extreme high temperatures experienced in the UK on 19th July 2022 resulted in a community of butterflies becoming inactive, but that shaded areas, including artificial slopes created as part of conservation management for climate change, provided a refuge during this period. Our results indicate that future high temperatures could force butterflies to shelter in the shade, potentially being unable to fly, feed or mate during these periods, with possible long-term impacts, particularly if multiple consecutive high temperature days are experienced.