In an attemp to contribute to a better knowledge of the leishmania-transmitting insect species in endemic areas of Paraguay, phlebotomes were collected by night catch. In this way, species of insects could be identified and natural infections could also be discovered. Six-hundred and six females bugs were examined, from among which the following species were identified: Lutsomia migonei (11%), L. shannoni (13.6%, L. intermedia (20.3%), L. wakeri (0.2%), L. whitmani (60.4), L. fisheri (2.6%), L. longispinosa (0.7%), and L. cortelezzi (0.2%). The last three species were first described in Paraguay. L. whitmani was the most frequently found species. Insect catch was performed in four Paraguayan localities in three endemic areas, using Shannon light traps and human bait, Leishmania promastigotes were found in the Malpighi tubes of a specimen of L. whitmani. All the other species mentioned above are also considered as vectors for Leishmania. Very little study has been performed on Phlebotomines in Paraguay. In 1955, González y Arce Queirolo collected 5401 specimens in endemic areas, Nad identified the following species: Ph. whitmani, Ph. migonei, Ph. intermedius, Ph. monticulosus, dnd Ph. pessoai (3). These species were cited by Barreto (1950) in his report on the distribution of phlebotomines in America (1). Between 1984 and 1985, A. de Arias performed an epidemiological survey in Tavapy (Alto Paraná), collecting the following species: L. intermedie, L. migonei and L. whitmani (6). Although all the species quoted by the different authors are considered vectors for Leishmania, they failed to find specimens infected with the parasite. In the present work we report some data on the species found in three endemic zones as well as the method of catch employed, and finally we mention some aspects of the natural infection