In the arid zone of Puebla-Oaxaca in Mexico, Dusky Hummingbird has been reported feeding on several species of columnar cacti as Polaskia chichipe, Stenocereuces stellatus, Marginatocereus marginatus, Neobuxbaumia mezcalaensis, N. macrocephala and N. tetetzo (Valiente-Banuet et al. 1996, 1997, Otero-Arnaiz et al. 2003, Dar et al. 2006). Also consumes nectar of Pseudobombax ellipticum and some agave in Morelos (Eguiarte et al. 1987). Other species included in the diet of Dusky Hummingbird are Castilleja and Opuntia.
Dusky Hummingbird also consume small arthropods (Wagner 1946), as probably do all species of hummingbirds (Remsen et al. 1983).