“leech.” The Hebrew word is aluqah (#05936 עֲלוּקָה), and although it only occurs this one time in the Bible, it is quite clear from the Aramaic, Arabic, and Ethiopic cognate words that it refers to the horseleech; also the Septuagint and Vulgate read “horseleech.”

There are different species of leeches, but Proverbs 30:15 almost certainly refers to the variety of leech referred to as the “horseleech.” That is why many older versions read “horseleech” (cp. ASV; English Revised Version; Geneva Bible; KJV). The horseleech was commonly found in Palestine and gets its name from the fact that it attached itself in the noses and mouths of horses that came to drink (it would also attach to humans who put their face in the water). They have such a powerful bite that they are not used in medicine to draw blood like other leeches. Also, they have two suckers, which may be the “two daughters” that Proverbs 30:15 speaks about who say, “Give. Give.”