In a project to determine the UK distribution of a conservation-status beetle Elater ferrugineus, 300 volunteers were recruited and supplied with traps containing a female pheromone that is an effective attractant for adult males. The occurrence and distribution of the insect were extended from previously estimated values and shown to be limited to a south-eastern area of the UK. In an attempt to account for the distribution, it was compared with a number of factors including climatic and habitat suitability. Of these, a major proportion of the variation in the distribution of E. ferrugineus was explained by temperature, that is, the beetle is restricted to an area delineated by a mean maximum summer temperature of greater than 21 °C.