Abstract
Marsh water was chemically analyzed in four habitats of Nannophya pygmaea Rambur in Ishikawa Prefecture, Japan. Somewhat acidic water (pH 5.7-6.4) was observed in one marsh, while the others often showed a higher value of pH (6.0-10.4). This result implies that suitable pH range for a habitat of the species is fairly wide including such a higher category, rather than recognized so far. Enrichment of mineral constituents such as Ca2+ compared to rainwater suggested that the marsh water was mainly supplied with ground water.