"This is an exciting and bizarre aspect of biodiversity that we have discovered in Denmark," study leader Jørgen Eilenberg, a biologist at the University of Copenhagen, said in a statement. "In and of itself, this mapping of new and unknown biodiversity is valuable. But, at the same time, this is basic new knowledge that can serve as a basis for experimental studies of infection pathways and the bioactive substances involved."

Eilenberg and his colleagues suspect that the fungi "dope" the flies with some substance that keeps them flying and active even as their abdomens are devoured from the inside out. Other fungi that prey on insects use amphetamine-type substances to keep their victims moving, so perhaps the newly discovered fungi do the same, Eilenberg said. The fungi might also produce antimicrobial substances that keep other pathogens away from the abdomen holes in order to keep the flies alive longer.