Medical Entomology and Zoology

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Two ponds in different enviroments were selected for the survey. The one, the Shinobazu pond, is located in the city of Tokyo, having crowded shops and residences in surroundings. There is no stream flowing in or out and the water is stagnant and somewhat muddv. The other, the Fujimi pond, is located in the suburb of Tokyo and is surrounded by woods. The water flows in from a corner and flows out from opposite side and is always clear. The Shinobazu pond (ca. 400m×250m) is larger than the Fujimi pond (ca. 400m×100m). The survey was made once a week during a period from May, 1948 to January 1949. In both the ponds, larvae appeared in May, gradually increased in number and gave rise to two seasonal waves. The first wave reached its maximum in the early summer or from the middle of June to the end of July. The second wave reached its maximum in autumn or from the middle of September to the middle of October. After this period the larvae gradually diminished inn umber and finally disappeared in the middle of December. When the seasonal periodicity of each species of Anopheles found in these ponds were considered separately, it is not the same with each other. Anopheles koreicus appeared in May, disappeared at the begining of July and reappeared from the end of August to the begining of October. In the latter period, edwardsi type of this species was also seen in small number. A. koreicus were seen in the Fujimi pond only, not being seen in the Sinobazu pond. This indicates that the species breeds in clear and rather cold water. A. sineroides appeared at the end of June and disappeared at the end of July in both the ponds, being never seen thereafter. A. hyrcanus sinensis was seen from May to Decerrber throughout in the case of Fujimi pond and from June to October, the whole period of the survey made, in the case of Shinobazu pond. All these findings are generally in accord with those reported by Matsubayashi and Sato (1943) in Setagaya district of Tokyo.

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