Malaria control has been directed towards regional actions where more detailed knowledge of local determinants of transmission is of primary importance. This is a short report on range distribution and biting indices forThe most important local vector species have been determined to be An. darlingi Root and An. albitarsis sensu lato. As we have not taxonomically determined the species in the albitarsis complex ourselves, hereinafter the species will be simply referred as An. albitarsis. Nonetheless, previous studies determined the An. albitarsis population in Jardim das Copaíbas, our study area, as An. albitarsis species E (Póvoa et al. 2006). Studies using entomological inoculation rates and biting indices have implicated An. darlingi and An. albitarsis as the most important vectors in the area (Silva-Vasconcelos et al. 2002, Póvoa et al. 2006.In this communication we describe seasonal variations in the biting rate of two main local malaria vectors in Jardim das Copaíbas a riverside settlement in the Northern Amazon Basin during one year. An equation describing the distribution range of An. darlingi during the rainy season was also determined.The study area Jardim das Copaíbas is a rural settlement (02°45'28''N, 60°42' 18''W) by the Branco River 5 km south of Boa Vista, the capital of the state of Roraima (Fig. 1B). Jardim das Copaíbas can be characterized as a savanna/alluvial forest landscape area. This is because the settlement is located in a savanna in close contact (~ 100 m) to a dense alluvial rainforest that delineates the Branco River. The area has a long rainy season (April-November), a short dry season (DecemberMarch), in which the Branco River water levels increase (Póvoa et al. 2006, Fig. 2). During the rainy season, the alluvial forest becomes partly flooded. Average yearly rainfall is 1100-1400 mm/year and temperatures are permanently high (daily average 27.8ºC) with little yearlong variation. Relative humidity is also high (daily average 73.8%) and varies little over the year (Furley 1994).In . Rainfall data and river water levels were registered (Fig. 2).The 1n + 1 transformed numbers of mosquitoes captured during peak biting activity (the first 4 h after sunset) were used during the rainy season for deriving an exponential regression function for An. darlingi distribution range. Estimations of the percentages of the adult An. darlingi population that could reach over specified distances were given by the expression: y = 4.435 exp(x*-0.003) (p < 0.001, r = 0.98) where x is the distance from the larval habitat and y the percentage of the adult mosquitoes. Since An. albitarsis also has larval habitat dispersed in the open savanna fields, a distribution range function could not be derived from the data collected. It was not possible to determine all larval habitats for each species. The transect represents the closest distance a certain mosquito would have to fly to reach the capture stations.