Horseleech

Morrish Bible Dictionary

Leeches are abundant in Palestine, and the horseleech may simply refer to a large species that would settle on a horse's foot if placed in the water where they abound. A horse has been known, in drinking, to get a leech into its mouth, which immediately began to suck its blood. The leech is used symbolically of a rapacious person, who is never satisfied, graphically delineated by the leech's two daughters, who say, 'Give, give.'  Proverbs 30:15 .

American Tract Society Bible Dictionary

The bloodsucker, a well-known water-worm; an apt emblem of avarice and rapacity,  Proverbs 30:15 . Cicero speaks of the horseleeches of the public treasury at Rome.