 An Elean myth told of how Herakles was troubled by flies when he was trying to sacrifice at Olympia, and was instructed in how to sacrifice to the Zeus who shoos away flies (Ἀπόμυιος), so that the flies were at once driven across the Alpheus.In cultivating Apollo at Leucas, a similar preliminary rite was enacted.Pliny says that when a swarm of flies is causing disease "(pestilentia)", the Eleans invoke Myacoris, and once the god has approved and accepted the sacrifice, the flies die immediately.