Sepsis cynipsea is a European species of fly and member of the family Sepsidae. It is a coprophagous fly that feeds on dung. These flies are most commonly found around freshly laid cattle dung where they eat and reproduce. Due to human agricultural practices involving cows, these flies are now common in other areas of the world.
Sepsis cynipsea has been studied extensively due to its sexual selection and reproductive practices. They exhibit sexual conflict: males compete for females and mount females to guard them for reproductive purposes. The females have been observed attempting to shake the males off.