You might think nothing smarts quite like a mid-summer yellowjacket sting but that’s some entry level pain according to entomologist Justin O. Schmidt who actually created a pain index, called the Schmidt Pain Index, that helps to compare the pain of various insect stings. Schmidt has been stung by 150 different species and these are his top 5. The Schmidt Pain Index ranks insect stings on a scale of 0 to 4 — 0 being no pain at all and 4 being blindingly excruciating. Here’s his top 5 Schmidt’s description of how bad it hurt.
5. Paper Wasp
“Caustic and burning. Distinctly bitter aftertaste. Like spilling a beaker of hydrochloric acid on a paper cut.”
Schmidt’s description of the least painful sting is enough to make you wince. The Paper Wasp gets its name from the material they use to build their nests. Because they feed on caterpillars and use fiber from plant stems to build nests, they can often be found in environments containing plants. Each nest may contain as many as 30 adult wasps.
4. Red Harvester Ant
“After eight unrelenting hours of drilling into that ingrown toenail, you find the drill is wedged in the toe.”
Red Harvesters are reluctant to sting but when they do it packs a punch.Red Harvester Ant nests are often located in open areas and resemble a flat, circular patch in the soil.
3. Warrior Wasp
“Torture. You are chained in the flow of an active volcano.”
This wasp is massive at over 2 inches long and has jaws bigger than its front legs. Don’t have to worry much though because this insect is predominantly found in South and Central America.
2. Tarantula Hawk
“Blinding, fierce, shockingly electric. A running hair dryer has been dropped into your bubble bath. A bolt out of the heavens. Lie down and scream.”
The Tarantula Hawk gets a 4.0 on the Schmidt Pain Index and with that description you can understand why. They grow up to 2 inches in length and the bright color of their wings acts as a warning to any potential predators. In the US they are often called “Spider Wasps” and are primarily found in desert regions. 
1. Bullet Ant
“Pure, intense, brilliant pain. Like walking over flaming charcoal with a 3-inch nail embedded in your heel.”
You might have heard of these little suckers being used in ceremonies marking the passage into manhood in the tropics and you can imagine the bravery involved. Bullent Ants are theants are the largest of the ant family, at about one inch in length. Their sting releases poneratoxin, a neurotoxic peptide that causes severe muscle contractions, a burning sensation, and great pain. OUCH.
image from westernexterminator.com