The Balanophoraceae is a unique angiosperm family that fully parasitizes the roots of trees. Although the pollination systems of several genera in this family have been reported, little is known of their diversity. In the present study, we investigated the pollination biology of Thonningia sanguinea (Balanophoraceae) in the tropical rainforests of Guinea, West Africa. Female flies of the families Muscidae and Calliphoridae as well as Technomyrmex ants frequently visited flowers to consume nectar secreted from inflorescences. While feeding, their bodies attached to anthers or pollen grains. The most abundant flower-visiting fly, Morellia sp. (Muscidae), was observed laying eggs on T. sanguinea, and the larvae fed only on the vegetative tissue of decaying male inflorescences. Our findings provide a new candidate of pollination mutualism involving plants that provide brood sites for their pollinators.