Despite the care taken in the abstract and discussion to highlight: "Findings are correlative rather than causal" and "evidence is required to determine if neonicotinoids are directly responsible for declines in national butterfly populations or are acting as a proxy for other factors associated with agricultural intensification", the authors seem to make a bold (and somewhat questionable) assertion here: "As most UKBMS sites are not in arable farmland, this favours the hypothesis that neonicotinoids are directly driving the declines in butterflies rather than acting as a proxy for agricultural intensification.". I am not sure of the logic here- it seems to be based on the fact that neonicotinoids may be transported in water but other factors of agricultural intensification will have more local effects. However, fertilising chemicals (N & P) can easily be transported in water courses and lead to eutrophication and reduced availability of low-fertility-associated plants which form the host plants for many butterflies. Additionally, as the authors even state themselves "However butterflies are mobile organisms and declines at UKBMS sites could occur if they are surrounded by farmland populations that act as population sinks". This is very true, so even local agricultural intensification can lead to butterfly population losses on non-agricultural sites. So I cannot see at all how the authors come to the conclusion that "this favours the hypothesis that neonicotinoids are directly driving the declines in butterflies"?