With the aim of analyzing the dispersion and degree of ecological plasticity of populations of Haemagogus capricornii Lutz, 1904, and Hg. janthinomys Dyar, 1921, in different phytogeographical areas of Brazil, from specimens originating from 32 municipalities, biostatistical analyses were carried out on female and male specimens by means of the Fager affinity index (1957) and the real dominance coefficient. Based on the affinity index, it was observed that the populations of these two taxa did not present any tendency towards sympatry. Based on the dominance coefficient, it was found from mapping the geographical distribution of the species that Hg. janthinomys is the dominant species in Brazil. However, in some geographical areas, such as Rio de Janeiro and probably São Paulo, Santa Catarina, and Rio Grande do Sul, Hg. capricornii is the species with greater dominance. The real relationship between the species with regard to geographical space reinforces the idea that the two species occupy different habitats.