The original description of Topomyia spathulirostris by Edwards (1923) included only the adult male and female. A redescription of these stages, as well as the previously undescribed male genitalia, pupa and larva are now made. Topomyia spathulirostris is transferred from the subgenus Topomyia to the subgenus Suaymyia on the basis of characters seen in the male, including the genitalia. This species occurs in rain forests and breeds mainly in bamboo internodes.