EVER been stung by a bee? You might not have thought so at the time, but the pain you felt was pretty average. On the Sting Pain Index 鈥� a league table of stings that ranks pain on a scale from 0 to 4 鈥� the honeybee scores 2 and is the benchmark against which all insect stings are measured. It鈥檚 bad enough to warrant a few expletives, but not to make you want to scream.
The index was compiled by entomologist Justin Schmidt of the Southwestern Biological Institute in Tucson, Arizona, who has spent 30 years comparing his painful experiences with those of fellow entomologists and friends. His most recent version ranks the pain inflicted by 78 species of stinging bees, wasps and ants. The index was never intended as a measure of human suffering, but as a way to gauge the effectiveness of an insect鈥檚 defences against predators. For a small animal, pain is the perfect weapon against larger predators. If it鈥檚 bad enough, the attacker will let go, and remember to avoid the species in future.
Assessing an animal鈥檚 pain is tricky, so Schmidt takes the human reaction to a sting as a guide to how it might feel to an animal. 鈥淚 think the pain would feel similar to most mammals, and lizards also exhibit aversive behaviour suggestive of extreme pain,鈥� he says.
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How do the various insect stings compare? Most fall far short of the honeybee鈥檚, either unable to penetrate human skin (scoring 0), or having no more effect than a stray spark (1). Common wasps and hornets rank alongside honeybees at 2. In category 3 are the burning stings of paper wasps and the piercing pain of the harvester ant, which once featured in the manhood rites of indigenous Californians.
At level 4 are (Pepsis wasps), which immobilise tarantulas with a sting before laying eggs in them. To a human, this sting is like a high-voltage electric shock, unimaginably excruciating and debilitating. Fortunately, the pain subsides in minutes. Also at 4 are warrior wasps (Synoeca), which inflict a pain so unrelenting you can think of little else for a couple of hours. Yet nothing rivals the sting of the (Paraponera clavata, see Picture), which causes wave after wave of burning, throbbing, all-consuming pain that continues unabated for up to 24 hours 鈥� bad enough to warrant a 4+.
鈥淣othing rivals the sting of the bullet ant, which causes wave after wave of pain鈥�
Is this degree of pain really necessary? Clearly it鈥檚 an effective defence: all three insects at the top of the Sting Pain Index are big and highly conspicuous, yet as far as Schmidt can determine, no vertebrate is prepared to eat one.
