Tropical Kingbird consumes both insects and fruit; aerial sallies for insects are the predominant foraging mode (Fitzpatrick 1980, Rosenberg 1990, Jahn et al. 2010a). Insects consumed include beetles (Coleoptera), bugs (Hemiptera), dragonflies (Odonata), grasshoppers (Orthoptera), bees and wasps (Hymenoptera, especially vespid wasps Vespidae), termites (Isoptera), butterflies and moths (Lepidoptera) (Eisenmann 1961, Haverschmidt 1968, Howell 1972, Fitzpatrick 1983, Voous 1983, P.C. Stouffer, personal observation). Based on fecal sample analysis, the main arthropod prey consumed at a site in Bolivia were insects of the orders Coleoptera, Hymenoptera, and Odonata (all present in at least 10% of fecal samples analyzed); kingbirds foraged on a greater variety of insects during the nonbreeding/dry season (Jahn et al. 2010a).
Fruits consumed are mostly arillate fruits and berries, including Bursera simaruba (Trainer and Will 1984), Ormosia isthamensis (Foster and Delay 1998), Cabralea canjerana (Pizo 1997), Stemmadenia donnell-smithii (McDiarmid et al. 1977), mistletoes (Loranthaceae; Haverschmidt 1968, Fitzpatrick 1983), peppers (Capsicum spp., Solanaceae; Haverschmidt 1968), Lantana camara (Verbenaceae; Leck 1971, 1972), Didymopanax morototoni (Araliaceae; Leck 1971), Tetracera spp. (Dilleniaceae; Leck 1971), figs (Ficus spp., Moraceae; Kantak 1979, Fitzpatrick 1983), and guava (Psidium guajava, Myrtaceae; Voous 1983). Also consumes fruits of Myrsine coriacea (Basler et al. 2009) and Myrsine lancifolia (Guerta et al. 2011), Miconia albicans (Allenspach and Dias 2012), and Trichilia claussenii (Athiê and Dias 2012), among those of other Neotropical plant species (Stouffer and Chesser 1998).