LogeionPerseus analysis of φθινύθεσκε:
φθινύθω (waste): imperf ind act 3rd sg (epic ionic)
LSJ entry
φθῐνύθω
φθινύθω [ῠ],
2. intr., waste away, decay, perish, of men, λαοὶ μὲν φ. περὶ πτόλιν Il. 6.327,
cf. 21.466,
Od. 12.131;
παυρότεροι . . φθίνυθον Il. 17.364;
τούσδε ἔα φθινύθειν, as an imprecation, 2.346;
also ἄχεϊ φ. παρειαί Od. 8.530,
cf. 16.145.