Like all hummingbirds, feeds on insects as well as flowers. Nectar from flowers likely to provide the bulk of calories. Short bill and small size are adaptations to feed on small low-yield flowers including numerous insect-syndrome flowers. Arthropods caught on the wing in typical hummingbird fashion, with perched bird suddenly sallying to catch one or more tiny flying insects. Not known to glean insects from foliage.
Feces are primarily of excess water acquired from nectar, and hard pellets of arthropod exoskeleton.
Flowers that the Scintillant has been seen visiting include (arranged by reference): Rubus rosifolius (page 12), Vaccinium poasanum (18), Impatiens walleriana (37), Stachytarpheta frantzii (39), Palicourea lasiorrhachis (67), Gonzalagunia rosea (140), Elleanthus glaucophyllus (141), Vaccinium poasanum (141), Clusia sp, Rubus sp. (Fogden and Fogden 2006); Salvia sp, Lantana sp, Hyptis sp, and Stachytarpheta sp (Stiles and Skutch 1989); Fuchsia sp (Clark et al. 2011); and Yucca sp (Wetmore 1968). This list is likely a small fraction of the species visited by the Scintillant Hummingbird.