• Main Chagas disease vector Triatoma infestans occurs in sylvatic environments of the Argentinean Monte ecoregion. • Triatoma patagonica , T. garciabesi and T. eratyrusiformis also occurs in sylvatic environments in the Monte ecoregion. • One T. infestans male was collected at fly distance to infested house. • None of the specimens was infected with T. cruzi. The eco-epidemiology of Triatominae and Trypanosoma cruzi transmission has been little studied in the Argentinean Monte ecoregion. Herein, we provide a comprehensive description of domestic and intrusive triatomines to evaluate the risk of reinfestation of rural dwellings. Triatoma infestans , T. patagonica , T. garciabesi and T. eratyrusiformis were collected by active searches or light traps. None were infected with T. cruzi. One T. infestans male was collected at 1.3 km from the nearest infested house. The finding of intrusive and domestic triatomines in sylvatic foci emphasizes the need of implementing an effective vector surveillance system. [ABSTRACT FROM AUTHOR]