No one really knows how many of them there are. There aren’t many scientists who specialize in studying them. They can spend much of their lives hidden inside the bodies of other insects. And since they specialize in body-snatching, they can be incredibly small. The smallest of them, the fairy wasps, parasitize millimeter-long insects, and are themselves no bigger than a single-celled amoeba. This means that when scientists try to catalog the number of insects in a given area, they often ignore all but the biggest and most conspicuous parasitic wasps.
Other insects, however, do not ignore them. It seems that every species of insect is targeted by at least one species of parasitic wasp—if not several. There are even parasitic wasps that exclusively target other parasitic wasps—they’re called hyperparasites. (They include the crypt-keeper wasp that was newly identified last year.) To Forbes’s knowledge, no insects have escaped these parasites. Even those that live under water have their own particular wasp nemeses.
True story. I almost tagged this #etymology. I must be tired.