ῥεκτήρ
From LSJ
εἰ γάρ κεν καὶ σμικρὸν ἐπὶ σμικρῷ καταθεῖο καὶ θαμὰ τοῦτ᾽ ἔρδοις, τάχα κεν μέγα καὶ τὸ γένοιτο → for if you add only a little to a little and do this often, soon that little will become great (Hesiod W&D, 361-362)
English (LSJ)
ῆρος, ὁ, (ῥέζω)
A worker, doer, like Homer's πρηκτήρ, κακῶν Hes.Op.191. 2 c. gen. objecti, worker in a thing, χρυσοῖο Man.1.297, cf. 4.149.
German (Pape)
[Seite 837] ῆρος, ὁ, der Thäter; κακῶν Hes. O. 193; sp. D., wie Maneth. 4, 149. 229.