Scarlet-thighed Dacnis is an arboreal omnivore, primarily eating small fruits and arthropods (Sclater and Salvin 1879, WIllis 1980, Hilty 1997, Robinson et al. 2000). It visits flowers for both nectar and insects (Carman and Martínez 2004). Stomach contents from two individuals contained fruit pulp and figs (Isler and Isler 1987). Of five stomachs examined from Panama, none contained more than 30% animal matter (Wetmore et al. 1984). It consumes fruit of Cecropia (Daily and Ehrlich 1994), Clusia and Zanthoxylum (Stiles and Skutch 1989), and Trema micrantha (Peralta 2007), as well as Miconia and Alchornea costaricensis (Greenberg 1981). It appears to prefer ripe black or blue Miconia argentea berries (Skutch 1962). It eats the fruits of Hampea appendiculata, Sapium oligoneuron, Dendropanax sp., and Acnistus arborescens (Wheelwright et al. 1984). It eats and perhaps disperses Xanthoxylum (Skutch 1962). It is a rare visitor to fruiting Ficus pertusa (Bronstein and Hoffmann 1987). It also eats the flower stems of Pourouma aspera (Wetmore et al. 1984). It regularly forages on fruits and at flowers of canopy epiphytes (Nadkarni and Matelson 1989).