Introdução: Triatoma sordida is widespread in Brazil and is the most frequent triatomine species found in households in the state of Bahia, where it was associated with Chagas disease outbreaks. Size changes are known triatomine adaptations to distinct microhabitats. Objetivo (s): We aim to evaluate morphometric changes in intra and peridomestic populations of T. sordida; we hypothesize that: 1) the wing size of populations captured indoors is smaller than that of peridomestic populations and 2) the sexual size dimorphism is smaller in house populations. Material e Métodos: We analyzed triatomines from different Regions of Bahia between 2013 and 2014. For the morphometric analysis, we selected specimens from the municipality of Barra, where indoor colonization was more frequent. The wings were mounted between slides, digitized, and edited for geometric morphometry analysis using TPSdig® and TPSrelw® software. We analyzed size variables according to the sex and habitat of individuals. We applied Principal Component Analysis (PCA) to explore wing shape variation. Resultados e Conclusão: We captured 410 specimens, from which we selected 120 individuals for morphometric analyses. We observed a significant size variation (t-test = - 4.04, p<0.01), with specimens captured in houses smaller than those in peridomicile. In addition, males and females from houses were more similar in size than those in the peridomicile, where females were larger, indicating a great wing size reduction effect in females. The PCA did not reveal evident wing shape differences between house and peridomicile populations. These results indicate that the house colonization by T. sordida is frequent in the municipality of Barra, Bahia and that the wing geometric morphometry can be applied to discriminate populations inside and outside houses and to quantify sexual size dimorphism. Our results reinforce the idea of analyzing sexual dimorphism to indicate house colonization and the hypothesis that T. sordida had successfully colonized houses in northeastern Brazil. We first describe and confirm T. sordida colonizing houses in Bahia and we suggest that wing geometric morphometry be applied as a tool to help detect domicile populations of T. sordida and house colonization in the future.