Butterflies and moths face a range of anthropogenic threats with many of the best-studied populations in decline. In response, butterfly and moth conservation programmes are implementing a diverse set of actions, but to date no study has synthesised evidence for their effectiveness. We present an overview of the recently published Conservation Evidence synopsis of butterfly and moth conservation, describe patterns and biases in the available evidence, and compare these to similar synopses on other taxa. We find that most evidence covers butterfly conservation, focuses on community-level responses, originates from the UK and the USA, comes from studies using the least robust designs, and assesses actions addressing the threat posed by agriculture. Far less evidence is available for moth conservation, for individual species’ responses, originates from Africa, Asia, Oceania and South America, comes from studies using the most robust designs, or tests actions designed to mitigate the impacts of pollution or climate change. While the geographic and study design biases reflect those found in evidence for the conservation of other taxa, the focus on community-level responses is higher than in any of the other synopses we examined. We suggest this may leave Lepidoptera conservation vulnerable to missing important, species-specific responses. We call for testing of conservation actions to be built into conservation projects for butterflies and moths, to build a robust evidence base for conserving Lepidoptera in a changing world.