Horse-leech

The horse-leech (Hebrew ʿalûqâ) appears only once in Scripture, in Proverbs 30:15, as an example of insatiable appetite: The horse-leech has two daughters crying 'Give, give'—the opening of a numerical saying about four things that are never satisfied (the grave, the barren womb, the earth thirsting for water, and fire). The identity of the ʿalûqâ has been debated; while traditionally rendered horse-leech (a large bloodsucking worm that clings to the throats of animals drinking), some scholars have proposed it refers to a vampire-like creature from folklore or simply a generic bloodsucker.

The Talmud identified the two daughters of the horse-leech with Gehinnom and the evil inclination, or with various allegorical pairs. The precise zoological identification matters less than the rhetorical function: the horse-leech's unceasing demand for blood (give, give) becomes the perfect image for insatiability. The broader Agur poem in Proverbs 30 uses natural observations to explore the limits of human wisdom and the mysteries of creation, and the horse-leech illustrates that some appetites are by nature inexhaustible.