Omnivorous; primarily insectivorous, but also consume berries. Beetles, especially dung beetles, were a frequent item in the diet at one site in Costa Rica (Skutch 1964); other prey items include large cicadas, phasmids (stick-insects), large green orthopterans, "larvae of various kinds," and, less commonly, spiders and small lizards (Skutch 1964). Orejuela (1980) examined the contents of 45 stomachs of Blue-crowned Motmots from southern Mexico (Campeche); a wide variety of prey was taken, but beetles constituted 53% of all items in the diet (but 52% by volume), followed by orthopterans (23% by number, 15% by volume). At this site, coleoptera were consumed in smaller numbers in the dry season, when consumption of orthopterans and homopterans increased.
Unusual records include predation on a long-tongued bat (Glossophaginae), which was swallowed whole (Chacón-Madrical et al. 2004), and of a hummingbird (Green-crowned Brilliant Heliodoxa jacula; García et al. 2006).
Solano-Ugalde and Arcos-Torres (2008) observed a motmot engaging in nocturnal foraging of sphinx moths (Sphingidae).