On the other hand, in Japan where kosa is brought, approx. 90 percent of kosa arriving is concentrated in the four months from February to May corresponding to spring, with almost no kosa observed in July to September corresponding to summer.
一方、飛来地側の日本では、春にあたる2月-5月の4ヶ月間に年間の約90%が集中し、夏にあたる7月-9月は全くと言っていいほど観測されない。