Triatomines are hematophagous insects that feed on the blood of vertebrates from different taxa, but can occasionally also take fluids from invertebrate hosts, including other insects. During the blood ingestion process, these insects can acquire diverse parasites that can later be transmitted to susceptible vertebrates if they complete their development inside bugs. Trypanosoma cruzi, the etiological agent of Chagas disease, and Trypanosoma rangeli are protozoan parasites transmitted by triatomines, the latter only transmitted by Rhodnius spp. The present work makes an extensive revision of studies evaluating triatomine-trypanosome interaction, with special focus on Rhodnius prolixus interacting with the two parasites. The sequences of events encompassing the development of these trypanosomes inside bugs and the consequent responses of insects to this infection, as well as many pathological effects produced by the parasites are discussed.