Many animals can walk up vertical surfaces or even along the ceiling. And many studies have examined how flies accomplish this impressive task. Whereas these studies have revealed the anatomy of the contact area and there have been many assumptions about the fly attachment mechanism, the main elements that contribute to the attachment force were unknown. However, Mattias Langer, J. Peter Ruppersberg, and Stanislav Gorb have successfully demonstrated that the fluid secreted from the fly's feet is a critical factor in attaching the fly to the ceiling.