The Schmidt Sting Pain Index or The Justin O. Schmidt Pain Index is a pain scale rating the relative pain caused by different Hymenopteran stings. It is mainly the work of Justin O. Schmidt, an entomologist at the Carl Hayden Bee Research Center. Schmidt has published a number of papers on the subject and claims to have been stung by the majority of stinging Hymenoptera.And follows with a listing of various stings on the pain index. Interesting. We have some little wild bee or wasp out here that I got stung by once, and at the time I thought a grassburr had poked me through my pants leg. I only realized I had been stung when I looked down to pick it out. I was stung so often by honeybees as a kid that their sting now is mostly just an annoyance. On the other hand, a red wasp sting will make me sick. I get nauseated and feverish, and the initial sting feels like someone stabbed me with a red-hot ice pick. Scorpions affect me similarly, but not as bad. I've never been stung by a yellowjacket.
His original paper in 1984 was an attempt to systematise and compare the hemolytic properties of insect venoms. The index contained in the paper started from 0 for stings that are completely ineffective against humans, progressed through 2, a familiar pain such as a common bee or wasp sting, and finished at 4 for the most painful stings. In the conclusion, some descriptions of the most painful examples were given, e.g.: "Paraponera clavata stings induced immediate, excruciating pain and numbness to pencil-point pressure, as well as trembling in the form of a totally uncontrollable urge to shake the affected part."
The problem with fire ants, of course, is that a bite from a single one isn't much of anything to worry about, but you don't usually get stung by only a single fire ant.