積雪地帯でのヤマトゴキブリの屋外越冬に関する一知見

抄録

Although Periplaneta japonica (Blattaria : Blattidae) is a common domiciliary cockroach in Japan, very few observations have been reported on the hibernation of this species. The authors found a lot of hibernating individuals of this species outdoors in a snowy area, Kashiwazaki, Niigata Prefecture. The cockroaches hid themselves in splits of decayed woods which had been piled up on the ground under a big tree in a farmer's garden and covered with heavy snow. All the cockroaches found were nymphs, 6mm to 23mm (final instar) in body length. The habitat is covered with snow for about 70 days every winter. According to the records of Kashiwazaki Meteorological Observatory, the daily lowest air temperature in this area is always below 0℃ for more than 2 months in winter. The final instar nymphs collected on 13th January and reared at 20℃ began to emerge into adults on 4th March.