The American species of Streblidae are divided into the subfamilies Nycterophiliinae, Trichobiinae, and Streblinae. The latter was erected by Speiser (1900) to house those streblid flies with a genal ctenidium. Along with the description of new genera and species, Jobling (1936, 1939) added to the subfamily, those streblid flies with the following characteristics: head subtrapezoidal or trapezoidal, posterior part of head as broad as the anterior margin of the thorax, rectangular thorax with a broad, shallow longitudinal groove in each anterolateral part, and mesonotum convex or flat, broader than the thoracic sternum. Jobling included in Streblinae the genera, Eldunnia Curran, Euctenodes Waterhouse (=Strebla Wiedemann), Metelasmus Coquillett, Paraeuctenodes Pessôa & Guimarães, Pseudostrebla Costa-Lima, Strebla (=Anastrebla Wenzel), and Stizostrebla Jobling. Wenzel et al. (1966) considered the shape and size of head and mesonotum convergent characters and switched Eldunnia, Pseudostrebla, and Stizostrebla to Trichobiinae, and restricted membership of Streblinae to those genera with a complete ctenidium, to include Anastrebla, Metelasmus, Paraeuctenodes, and Strebla. Herein, using cladistic methods, I test the hypotheses of Jobling (1936, 1939) and Wenzel et al. (1966) regarding the delimitation of the subfamily, and explore the ctenidium in a phylogenetic context.