Early in his career, Justin Schmidt realized he had a problem.

Schmidt, a budding entomologist, and his zoologist wife had just returned to the University of Georgia from a trip around the country.

They'd been collecting different species of harvester ants, "nasty stinging insects whose venom chemistry was unknown," as he describes them in his fascinating new book, "The Sting of the Wild."

To learn the details of the venom for his dissertation, they had to analyze incredibly large numbers of the creatures, which meant getting up close and personal with them.

Debbie, Schmidt's wife, describes her first harvester sting in the book as a "deep ripping and tearing pain, as if someone were reaching below the skin and ripping muscles and tendons; except the ripping continued with each crescendo of pain."

After collecting buckets of the creatures, the plan was to analyze them and compare the venoms from different specimens. To assess venom, Schmidt needed to evaluate both toxicity and pain. Toxicity was straightforward — already existing measures could be used. But there was no existing scale to measure the pain of insect stings.

Thus was born the "Schmidt Pain Scale for Stinging Insects." It was a four-point system, anchored by the well-known sting of a honey bee (rating a two), something people all over the world could be familiar with. To go up or down a full point, a sting had to be discernably more or less painful than the stings on another level. Half points could be used for pricks that fell somewhere between levels.

Over the years, Schmidt added new species to the list. He mostly didn't try to get stung. It just happened, more than 1,000 times, from at least 83 different species that have been evaluated on the index.

We've picked out insects that will illustrate the full scope of the scale, including a few that demonstrate the worst of the worst: