Based on a survey on the presence of P. megistus in several localities of Maranhão State, performed by the National Foundation of Health, from 1982 to 1995, the distribution of this species is shown. The capture of the adults and nymphs in the domestic environment was the basic method employed. The process of capture started at the rear and finished at the front of the human dwellings, and the surroundings as patio, back yard, garden, harbouring chickens, were inspected afterwards. All the specimens collected were identified. An effort was made to try to detect Trypa-nosoma from the intestinal content of some bugs. Maranhão is made up of 136 municipalities and the survey covered 87 of them. Panstrongylus megistus was in 14 municipal districts which belonging to the savana zone (cerrados) in the southern portion of the State. In total, 1,632 specimens of P. megistus were captured and 277 were examined resulting in the rate of 1.1% of infection with Trypanosoma cruzi. São João dos Patos (22.4%), Pastos Bons (15%), São Raimundo das Mangabeiras (14.5%), Mirador (14.3%), Riachão (8.3%) and Loreto (6.2%) were the municipal districts in which the presence of P. megistus was more common. For the moment, P. megistus is found only in south-east and south of Maranhão. Judging by the current distribution this specie penetrated through the "cerrados" from of the neighbouring states of Goiás, Tocantins and Piauí.
Triatominae; Panstrongylus megistus; Distribution; Chagas disease; Maranhão