In the present work, we investigated whether it is possible to detect morphometric changes in Rhodnius neglectus Lent, 1954 (a candidate vector of Chagas disease in Central Brazil) populations in the transition from sylvatic to laboratory conditions. We analyzed size and shape variation in wings of sylvatic parents and their laboratory descendents (first, third and fifth generations) using geometric morphometric techniques. Sexual size dimorphism and shape of wings were maintained, but wing size decreased from sylvatic specimens to their laboratory generations. Size variation in R. neglectus should reflect the expected morphometric changes between sylvatic and domestic populations and can be applied to analyze the level of adaptation of R. neglectus to domestic habitats. This information might be useful to detect persistent infestations in dwellings after insecticide application, or new infestations from the sylvatic environment, and is therefore important to guide vector surveillance strategies for Chagas disease.