Abstract
The damselfly, Mortonagrion hirosei, was designated as an endangered species by the Environment Agency in 1991, because its habitat is vulnerable to the effects of land reclamation and river improvement. The effects of reed cutting on the population of the damselfly were studied in Tsurue river mouth, Haramachi Ward, Minamisouma City in Fukushima Prefecture. In the investigation in 2003, the adults of the damselfly were found on both shores of reed bed beside the Noma bridge of Tsurue river. However, the adult of the damselfly was not found in 2005. Also, there were no larvae found on the both shores after the reed cutting in March 2003. It was concluded that the extinction of the damselfly was caused by the reed cutting, which was flushed away dead leaves and stems of reed plants to egg laying and habitat of the damselfly.
