of the Maricopa harvester ant as having a pain level of 3, describing it as such: "After eight unrelenting hours of drilling into that ingrown toenail, you find the drill wedged into the toe." Pain Level 4 Pain Level 4 is the highest level in the Schmidt sting pain index. Schmidt's original index rated only one such example, the sting of the bullet ant, as a 4. Schmidt described the sting as "pure, intense, brilliant pain...like walking over flaming charcoal with a three-inch nail embedded in your heel." The bullet ant's venom primarily contains poneratoxin, a paralyzing neurotoxic peptide. Schmidt later gave the sting of a tarantula hawk species, Pepsis grossa, a rating of a 4, which he described as "blinding, fierce [and] shockingly electric", though the duration of pain from the sting is short-lived, lasting only approximately five minutes. The composition of tarantula hawk venom is unknown. Schmidt also later rated the sting of a species of warrior wasp as a 4, describing it as "Torture. You are chained in the flow of an active volcano. Why did I start this list?", saying the pain lasts up to two hours. Evolution from painful to toxic stings The Schmidt sting pain index arose from the pursuit of a larger hypothesis: that the evolution of sociality in Hymenoptera was dependent on the evolution of venom that was both painful and toxic. Pain is an advertisement of damage in the body, but molecules that produce pain and those that are toxic, and actively cause damage, are not the same. Although the painful signal acts as a deterrent, intelligent predators learn the dishonesty of this signal with repeated exposure – that there is no real damage being done. For the early Hymenoptera that were primarily solitary, the pain alone would allow them the chance to escape. Furthermore, solitary insects do not provide a high energy reward for predators, and therefore predators do not expend significant effort to hunt them. However, with the evolution of sociality where many Hymenoptera cluster together in colonies, nests become a nutritionally rich and therefore worthwhile target. If there were no defences, predators would devour the defenceless society, leaving few surviving individuals. Sociality would therefore not be beneficial. In order for sociality to evolve, Hymenoptera needed a defence beyond a painful sting to protect their whole colony. Their sting was an advertisement of damage, and toxicity evolved as its