Large numbers of male and female Bay checkerspot butterflies, Euphydryas editha bayensis, were observed taking moisture from the banks of a seasonal creek in 1990.Previous observations of this long-studied subspecies imply that taking moisture from saturated substrates is not a common behavior for males, and is certainly not the norm for females.This study found that during the early and mid-portions of the adult flight season in 1990, a large number of older individuals visited the creek site, and that many butterflies were apparently flying more than one kilometer round-trip to visit the creek site.This behavior may have been induced by drought conditions.This communication reports numerous observations of a butterfly, the Bay checkerspot {Euphydryas editha bayensis ) , not typically thought to be a "puddling species."Although adults, and males in particular, of many species of Lepidoptera have been observed extracting fluids from moist soils (Adler