Five strains of Trypanosoma cruzi: were studied 2 of region non endemic for Chagas disease (isolated from marsupiais) and 3 of endemic region (from man, marsupial and dog). The susceptibility of the triatomines was tested in the Vinstar. The blood meal of Triatoma brasiliensis and Rhodnius prolixus was 0,09 g; Triatoma infestans and Pnastrongylus megistus have sucked 0,13 g. The third specie of bugs became highly infected with ali the strains of T. cruzi tested; the second and third were the less infected and the fourth has showed intermediate rates. The strains most infective are those of marsupials and the less infective is originated from dog.