SUMMARY.Certain larvae and pupae have been identified asNotidobia ciliaris(Linné) by rearing field‐collected larvae to the adult stage and by rearing larvae from eggs laid by a female in captivity. The larvae differ in many important respects from larvae of this species described by earlier workers. Characters are provided to distinguish these larvae and their associated pupae from those ofSericostoma personatum(Spence). The habitat and distribution of both species in Britain is outlin