The blue wasp was a completely new species, and Weinersmith and Egan named it the crypt-keeper wasp. It’s a stunning example of a hyperparasite—a parasite whose host is also a parasite. This lifestyle is surprisingly common, especially among wasps. Many species lay eggs in the bodies of other insects, only to have other wasps lay eggs in their young. And sometimes, hyperparasites can be parasitized by other hyperparasites, creating hierarchies of bodysnatching that can grow to four tiers.
Even by these standards, the crypt-keeper wasp is special. Parasites are incredibly common, but only some manipulate the behavior of their hosts. There are fungi that turn ants into zombies, hairworms that compel crickets to jump into water, and tapeworms that force shrimp to swarm in groups—all to help the parasites spread to their next hosts. The crypt-keeper wasp does this too, but as Weinersmith and Egan have shown, it’s one of the few known hypermanipulators—parasites that manipulate the behavior of other manipulative parasites.
Somehow, the crypt-keeper wasp can find an oak tree that already contains the larva of a crypt gall wasp, and then lays an egg inside the crypt. Once hatched, its larva manipulates its orange crypt-mate into chewing an escape hole that’s smaller than usual. The orange victim then plugs the small hole with its own head, while the crypt-keeper larva devours it alive. Eventually, the crypt-keeper turns into an adult and chews its way to freedom, through the head of its roommate/larder/wall-plug.
Because of its behavior, Weinersmith and Egan gave the wasp the formal name of Eudurus set, after Set, the Ancient Egyptian god. “Set was the god of chaos and evil, and he was said to control other evil beings,” says Weinersmith. “He also locked his brother Osiris in a crypt for him to die. It kind of blew our minds how many cool connections we could find.”
After discovering the crypt-keeper, Egan went to the American Museum of Natural History and looked at old collections of gall wasps that had been gathered by Alfred Kinsey. (Yes, that Kinsey; before becoming synonymous with human sexuality, he was a prolific gall-wasp aficionado, who collected millions of the insects.) In some of the stored branches, Egan saw little heads plugging holes. We’ve found several such samples in museums around the country, going back 100 years.”
“This is the type of science I love; it leaves us hungrily asking more questions,” says David Hughes from Pennsylvania State University, who studies manipulative parasites. For example, “how does this wasp get its egg into its soon-to-be excavator? And how does it do that so precisely to stop the activity at a stage where the hole is large enough just for a head to block, but not for the body of the manipulatee to emerge?” It might secrete some kind of mind-addling chemical. Alternatively, it might just eat its host to the point when it still has enough energy to make an escape hole, but not enough to make a big one.