The following conclusions were drawn: 1. After sunset the Kerteszia become more active in the tree tops and with the changes of the microclimatic conditions of the begining of the night, they leave the forest in great numbers. 2. In the unsprayed localities the proportion or Kerteszia that feeds indoors are not significantly different of that observed for A. gambiae in Africa. For the zoophilic anophelines, such as A. strodei, this proportion is at least two times higher. However, even before the introduction of residual insecticides the Kerteszia were not endophilic mosquitos. 3. Some data about the deterrency of DDT for the Kerteszia are very high, other are similar to those observed in A. gambiae. It was observed that the Kerteszia are deterred by very small doses of DDT. 4. Only a small proportion of the Kerteszia that feeds indoors, rest on the walls, the majority flies diretly to the persons and after the blood-meal flies outside. the time of contact with sprayed surfaces is same observed for others anophelines, generally less than 10 minutes; 5. The activity of Kerteszia is different of others malaria vectors because they are more active in the begining of the night, when is more probability of existing people outdoors. 6. The study of the man-bitting rate showed that, even in the unspraved areas, the outdoor component is always higher. In the sprayed localities the ratio outdoors/indoors component may reach rates up to 10. 7. The prophylactic works of the "Serviços Nacional de Malária" already showed that, even with distribution of medicines, the diminution of man-bitting activity inside the sprayed dwellings and the toxic action of the insecticide, are insufficient to interupt malaria transmition. This fact with the data of the outdoors catches, suggest research on methods for decreasing Kerteszia densities in the proximity of the human dwellings.