According to Justin Schmidt’s sting pain index, the bullet ant has the most painful ant sting. The species is Paraponera clavata, a large tropical ant found in Central and South America.
Schmidt rated its sting at level 4, the highest level on his original 1-to-4 scale. He described the sensation as intense, burning, and persistent, which inspired the common name “bullet ant”: victims have compared the pain to being shot. The venom contains poneratoxin, a neurotoxic peptide that affects voltage-gated sodium channels and contributes to prolonged pain.
The index is a subjective scientific ranking based on Schmidt’s personal experiences, not a universal medical measurement. Later versions included other insects at level 4, including certain tarantula hawks and warrior wasps, but the bullet ant remains the highest-rated ant.
Carpenter ants generally have much milder stings. Harvester ants can be extremely painful, while red fire ants cause burning and pustules, but neither is the classic level-4 ant on Schmidt’s index.