We analyzed 64 quantitative and qualitative morphological characters in different populations of Lutzomyia (Nyssomyia) umbratilis Ward & Fraiha from Venezuela (Gran Sabana, Bolívar/BO) and Brazil (Serra do Navio, Amapá/AP, Manaus, Amazonas/AM, Monte Dourado, Pará/PA, and Peixoto de Azevedo, Mato Grosso/MT). Based on an analysis of qualitative characters, no differences were observed that could distinguish between the populations. Parametric tests were used to verify differences between sample means and variance homogeneity. The analysis-of-variance (ANOVA) test showed the existence of differences between character means in the five populations. In the graphic representation of the Student-Newman-Keuls test (Student–Newman–Keuls), we observed that 77% of the analyzed characters displayed disjunctions between the Venezuelan and Brazilian populations. Considering only the Brazilian population averages, we concluded that they are statistically different. When the Student–Newman–Keuls test was applied, no pattern was found that could separate them. However, in part, the phenetic analysis showed some evidences of heterogeneity in MT population.