Witnessing hundreds of Calliphora nigribarbis in migratory flight and landing in Nagasaki, Western Japan

Abstract

In the autumn of 1995,we had an opportunity to witness and evaluate the importance of the mass, probably transoceanic, migratory flight and landing of Calliphora nigribarbis Vollenhoven in the campus of Institute of Tropical Medicine, Nagasaki University, Nagasaki, Kyushu, western Japan. On October 25 (14 : 30 to 17 : 30,fine) and 26 (10 : 30 to 17 : 40,fine), they were seen flying in large numbers from the northwest to southeast across the top of the laboratory building (about 10m in height). They flew continuously in the direction of the wind and we caught some of them at the top of the building. They flew vigorously, with many flying well beyond the reach of our insect nets and without changing course. Some flies reaching the building in the evening landed on the concrete wall of the building. The migratory flights were simultaneously observed in Fukuoka where the flies were seen flying from the north across Tsushima-Kaikyo Strait. Fukuoka and Nagasaki are situated about 250 to 300km southeast of the Korean Penninsula. It could be inferred that these flies migrate across from the Asian continent to the main island Kyushu. C. nigribarbis has been considered to migrate altitudinally in the mainland Japan. However, the number of flies found in autumn (November) in Kyushu appears to be also increased by the transoceanic migration.