To procreate, a jab will sting a host, which deposits eggs below the surface of the skin. The eggs will grow into larvae, eventually leaving the skin. If a humanoid was stung, it could produce vomiting and diarrhea in its victims.
In 2258, a dispute arose between Farmer Jae and Farmer Nee, in which Jae believed that Farmer Nee's Jab had stung Des, his prized swug. Elric and Galen helped investigate, discovering that the Jab had not stung Des.