Abstract
The larva and the pupa of Lenarchus fuscostramineus SCHMID are described here for the first time. The general morphology of the larva mostly agrees with the character of the genus provided based on North American species by WIGGINS (1977). The larvae live in small shallow springs and seeping areas and feed on highly decomposed plant material. We established that the larvae described as Lenarchus sp. LA from Honshu by TANIDA (1985) were a misidentification of Nothopsyche sp. NA.