In Castro Alves, Bahia, Brazil, the presence of children seroreactive to Trypanosoma cruzi was associated with high infection rates in household Panstrongylus megistus (Hemiptera: Reduviidae). In a survey of 63 infested houses, 54% of bugs collected from houses with seroreactive children were infected. In contrast, only 14% of triatomines from houses with seroreactive adults and no seroreactive children were infected. Infection rates in P. megistus were significantly correlated with the number of seroreactive children present per household. To selectively reduce transmission of T. cruzi in a community, protection of infested homes housing children should receive primary attention.