The Biology of Amazonian Anophelines an Evaluation of the Occurrence of Species of Anopheles, and Other Culicids at the Balbina Hydroletric Dam - Five Years After the Filling of the Reservoir. An entolomogical study was conducted in the area of influence of the Balbina Hydroelectric Dam (UHB), situated about 146 km from Manaus, Amazonas, in order to evaluate the effect it might have on populations of Anopheles and other culicids. Five years after the lake was formed, An. darlingi, An. nuneztovari and An. triannulatus were the most frequently encountered species. Collection areas were: 1 - Road BR-174, 2 - Access to UHB and 3 - Uatumã-Morena Area. The mosquito/man/hour for each specie in the three areas were respectively: Area 1 - 0,57; 12,85; 0,43. Area 2 - 0; 3,75; 0,18 and Area 3 - 0; 26,38; 0,34. Representatives of the first two of these species were found to be positive for Plasmodium by using an immunoenzymatic test. The prevalence of positive mosquitos was 1:35 for An. darlingi and only 1:548 for An* mmezjovciri. The density of the other culicids was low even though the diversity was comparable ( 32 different species) to that found in the areas of other hydroelectric dams built on clear or white water rivers in Amazonia. In the black waters of Balbina, an initial proliferation of macrophytes was followed by a reduction in these plants possibly caused by lack of nutrients in the water. The fall off in macro-phyte production relates to a scarcity of Mansonia sp. in the area.