On the oviposition of Aeshna viridis Eversm. (Anisoptera: Aeshnidae)

It has been suggested (e.g. D. GLITZ et al„ 1989, NatSchulz LandschPfl. Hamburg 26, p. 50) that an area of at least 5 m2 of water soldiers (Stratiotes aloides) is a precondition to stimulate oviposition in females of A. viridis. Observations made in the St. Jiirgensland NE of Bremen, Germany, indicate that this statement might need reconsideration (H. FLIEDNER, 1-995, Hagenia 9: 16-17). Originally fen-lands, this area near the river Wiimme has been drained by numerous ditches and turned into pastures. Since 1980, Stratiotes, once common there, has almost completely disappeared, probably due to hypertrophia as well as to the frequent clearing of the ditches.