As a consequence of Triatoma infestans eradication in Argentina, Chile, Uruguay and Brazil, these countries are considered free from Trypanosoma cruzi vectorial transmission, but the adaptation of wild triatomine species to human dwellings and recolonization by surviving insects after spraying deserve a continuing follow up. Considering an endemic area of Chagas disease in northeast Brazil, Joao Costa in Piaui, T. brasiliensis, T. pseudomaculata and, more rarely, T. sordida were collected in domestic and peridomestic habitats to evaluate the blood source and the infection rate by T. cruzi. The major hosts of all triatomines were birds, rodents, dogs and marsupials. The RAPD analysis of specimens of the predominant species, T. brasiliensis, showed a very homogeneous pattern of peridomestic and domestic populations that differed from that of T. brasiliensis collected in another county, 50 km away. Only T. brasiliensis colonized human dwellings, and 5.6% of the bugs were infected with T. cruzi that belonged to T. cruzi groups I and II, according to the biochemical and molecular characterizations. Our results emphasize the importance of maintaining vector surveillance and control programs.