Bee-keepers and the crop producers they serve have been plagued worldwide by the mysterious disappearance of the European honeybee Apis mellifera. Various causes have been touted for this 'colony collapse disorder', including pesticide use, viruses and mites. Mariano Higes of the Regional Apiculture Center in Marchamalo, Spain, and his collaborators had previously fingered a gut-infecting fungus, Nosema ceranae, as a suspect. More recently, while studying two embattled Spanish apiaries 750 kilometres apart, they found N. ceranae to be the only likely suspect. Moreover, at these apiaries, the fungicide fumagillin halted colony collapse and cleared the infection from existing colonies. Although these results are promising, N. ceranae may not be to blame for all cases of colony collapse.