In Greek mythology, Ascalaphus (Ancient Greek: Ἀσκάλαφος) was the son of the underworld river-god Acheron and the nymph Orphne (or Gorgyra), custodian of Hades' orchard. He revealed that Persephone had eaten pomegranate seeds in the Underworld, binding her to return each year; Demeter punished him by burying him under a rock, and after Heracles freed him he was transformed into an eagle owl. He is distinct from Ascalaphus son of Ares, the Minyan leader at Troy.
Adapted from Wikipedia, "Ascalaphus (son of Acheron)" · CC BY-SA 4.0
I.Mythology
Ascalaphus, son of Acheron and Orphne, kept Hades' orchard. When Zeus ordered Persephone's return from the Underworld, Ascalaphus testified that she had tasted pomegranate seeds there; because she had eaten food of the dead, she was obliged to spend part of each year below — four months in some accounts, six in later versions.
Demeter in anger buried him beneath a heavy rock in the Underworld. When Heracles descended, he rolled the stone away and released him; Demeter then transformed Ascalaphus into an eagle owl. Another version has Persephone herself change him into an owl by sprinkling him with water of the Phlegethon. Ovid calls the resulting bird "the vilest bird; a messenger of grief; the lazy owl; sad omen to mankind," and as an owl he becomes a familiar of Hades.