The UK’s Big Butterfly Count starts this week. Will air pollution improvements during lockdown increase your chances of seeing rare butterflies and moths? The best-known connection between Lepidoptera and air pollution is the peppered moth story. Dark forms appeared in industrial towns across the UK in the mid-1800s, and 50 years later about 90% of peppered moths were dark. It is thought these were better camouflaged, and therefore less likely to be eaten by birds, as they rested on trees that were blackened by air pollution and denuded of lichens. But, as air pollution improved, lighter-coloured moths increased in the UK and US. The disappearance of half of the butterfly species from Epping Forest, London, in the 19th and early 20th centuries was partly attributed to air pollution. Following the 1956 Clean Air Act, some species, including the purple hair streak, gatekeeper and speckled wood, returned. Further afield, the six-mile (10km) Kola peninsula around the Monchegorsk steelworks in Russia, became a largely butterfly-free zone in the 1990s. All wildlife suffered from acid rain from coal burning but butterflies seemed more sensitive than many plants. Today, our butterfly habitats are also being damaged by soil fertility changes caused by air pollution from traffic and farming.