billbug, (subfamily Rhynchophorinae), any stout-bodied beetle of the family Curculionidae (insect order Coleoptera) that has a short snout and body length up to 5 cm (2 inches). Some (e.g., Rhynchophorus) are found mainly in the tropics, boring through the new growth of palm trees. The larvae of R. cruentatus are about 5 cm long and make a clucking sound while boring in cabbage palms. These larvae are eaten, either fried or raw, by native peoples of tropical America. A similar species (R. ferrugines) has threatened copra (dried coconut meat) production in the Pacific because it attacks coconut and wine palms.
Other billbug genera include Diaprepes, Rhodobaenus (cocklebur weevils), Sitophilus (granary and rice weevils), and Sphenophorus (corn billbugs).