八丈富士にみられるケブカクロバエの発生消長

Abstract

An investigation was made to know the life history of Aldrichina grahami (Aldrich, 1930) in Hachijo Island, Tokyo, from February 1981 to May 1982. A trap baited with horse meat was set at five different altitudes, 50m, 200m, 400m, 600m and 800m, of Mt. Hachijo-Fuji. The number of flies captured was counted once a month. The larvae and pupae which had bred from meat in the trap were also counted and transferred into a separate trap for emergence. The number of the flies gradually increased from foot to top of the mountain during March to May. Following the rainy season in June, the number decreased and only one female was trapped at alt. 600m during August to September. Some females were captured again at alt. 600m and 800m in October. This suggests that some of mated females can estivate in the mountainous area above alt. 600m where it is usually cool and foggy during summer and mossforests develop. A few adults and a number of pupae were found even in winter in the trap of station 600m. The upper region of the mountain may be considered as a primary habitat of this blow fly. After estivation some females probably migrated for spawning eggs from the mountainous habitat and appeared in the town at alt. 50m. They may be successful in finding enough foods and breeding places around the human dwellings in winter and spring. The 74% of the flies were trapped in a temperature range of 2.0-9.0℃ in minimum and 16.5-23.0℃ in maximum and in a range of day length 10 : 30-14 : 20. This also suggests that the adult has a preference for such climate as being rather cool before sunrise and warm in daytime in spring and autumn.