There are about 18,000 species of wasps in North America. Roughly 20 of them can hurt you. The wasps people fear are all from one family: Vespidae. They make up less than 1% of wasp species on the continent. They build the visible nests, they defend them aggressively, and they're the ones you remember from a bad encounter. The other 99% live solitary lives and ignore humans entirely. Many can't sting at all. Many more have stingers but never use them on people because they don't have a nest to defend. What they do instead is hunt other insects. A single mud dauber stocks her nest with paralyzed spiders, including widows and recluses. A braconid wasp lays eggs in tomato hornworms. An ichneumon wasp parasitizes wood-boring beetles that kill ash trees. A cuckoo wasp infiltrates the nests of other wasps and bees. Some species control aphids; others control caterpillars, beetle grubs, or flies. Most agricultural pest insects in North America are controlled, in part, by parasitic wasps that almost no human ever sees. There are over 25,000 species of ichneumon wasps alone, and they keep entire orders of insects in check. The five or so wasp species that ruin a picnic in late August are real. The 17,995 species that are running the pest control infrastructure of an entire continent get almost none.