The bumblebee hummingbird is long and weighs ; it is one of the smallest hummingbirds.Arizmendi, M. d. C., C. I. Rodríguez-Flores, C. A. Soberanes-González, and T. S. Schulenberg (2021). Bumblebee Hummingbird (Selasphorus heloisa), version 1.1. In Birds of the World (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.bumhum.01.1 retrieved July 28, 2022 Both sexes of both subspecies have a short, straight, blackish bill and a small white spot behind the eye.
