Metaphorical language pervades Tertullian’s Scorpiace, a polemical treatise written in response to so-called “Valentinians” and “Gnostics” who oppose the practice of martyrdom. To sharpen the sting of his polemic, Tertullian makes use of an elaborate arachnid metaphor, in which heretics are likened to scorpions, heresy to venom, and impressionable members of the church to prey. Scholars often handle Tertullian’s metaphorical language in one of two ways: some use it to gauge the extent of his medical knowledge; they ask how familiar Tertullian is with the medical tradition, and to what degree he understands Christian faith and secular medicine to be compatible. Others focus more upon the dispute between Tertullian and his opponents and summarily dismiss his metaphorical language as superfluous rhetoric. This paper takes a different approach, one that does not divorce Tertullian’s metaphorical language from his polemic. By drawing upon the notions of intertextuality and conceptual metaphor, this paper argues that Tertullian’s application of a scorpion metaphor through a rewriting of Nicander’s Theriaca, a Hellenistic treatise on animal toxicology and therapeutics which Tertullian mentions at the beginning of Scorpiace, allows him both to depict the landscape of early Christianity as an anti-bucolic world infested with venomous scorpion/heretics and to aver that heresy poses a threat not only to the minds of Christians but also to their bodies.