Abstract
Malaria vector occurrence in mountainous villages was monitored for 2 years in north Thailand. Both larval and adult densities of Anopheles miniumus peaked in May or. June and in November or December. Stable conditions in streams during these periods possibly favored the breeding of An. miniumus. Higher lalval density also was encountered in streams where ca. 3/4 of the water surface was sunlit, portions with rapid currents and slow currents alternate, and the water was clear. An. maculatus sensu lato peaked in June or July, while An. dirus scarcely changed seasonally. The densities of the three malaria vectors were higher in more mountainous villages.
