New data on stage-frequency analysis of Triatoma sordida in spontaneously developed colonies confirm those former by published concerning adult dispersal and survival rates. Average nymph stage period was longer than that previously observed; consequently the total length of first to fifth nymph stages reached nearly one year. This difference may be due to the greater number of colonies observed, which were developed in five experimental chicken coops, thus making the data more representative. The total period of the fifth nymph stage was 99 days. Annual period of adult dispersal was defined by computing data available from previous research on this species and Panstrongylus megistus. Distinct cycles were defined for both these triatominae bugs. T. sordida show clear dispersal activity starting in March and continuing until May. During the July-August period, T. sordida nymphs in the first stages start to increase and tend to become predominant. For P. megistus, adult dispersal begins in October and continues until November, and the first nymph predominance occurs during November-December period. Therefore, these two-month periods, that is, July-August for T. sordida and November-December- for P. megistus, seem to be the best dates for surveillance activities, at least in the southeastern region of Brazil.
Trypanosomiasis South American; Triatoma sordida; Panstrongylus megistus; Triatominae; Triatominae; Ecology
