Meet Cyranorogas depardieui. It's a wasp, but not like any wasp you've ever seen. Its face has a sharp ridge, like the blade of a knife, sticking out of it.  The new wasp was discovered during an expedition to Mount Wilhelm, the highest mountain in Papua New Guinea, in 2012.  It has now been formally described in the Journal of Natural History by Buntika Butcher and Donald Quicke of Chulalongkorn University in Bangkok, Thailand.  "The wasp is very unusual," says Quicke.  The species name contains two jokes about big noses. "Cyranorogas" refers to Cyrano de Bergerac, a 17th-century French playwright who supposedly had a large nose, while "depardieui" refers to the actor Gérard Depardieu, who played Bergerac in a 1990 film.  It's not clear what the face blade is for. Quicke says the wasps might pupate inside the bodies of caterpillars. If that's true, the blade might help them escape once they've hatched. These wasps, he proposes, might use the blades to cut open caterpillars from the inside.  C. depardieui belongs to a large family of wasps called the braconids. Most of these wasps are parasitoids: they spend much of their lives inside the bodies of other animals, which generally wind up dead as a result.  C. depardieui is a member of a braconid group called the Rogadinae. They have a tendency to mummify their hosts.  In all the Rogadinae species that have been studied, the females lay their eggs inside the bodies of caterpillars. When one of the wasp larvae hatches, it eats the caterpillar from the inside. Finally it kills the caterpillar and mummifies it, and builds itself a cocoon inside the mummified corpse.  Inside this cocoon, the larva metamorphoses into an adult wasp. When it's done, "the adult chews its way out of the caterpillar mummy, making a small round hole at one end," says Quicke.  That may explain why the wasp has a blade on its face. "The strange face, which has this sharp, even minutely-serrated blade, is therefore possibly used to cut its way out once it has metamorphosed," says Quicke.  It's not clear why C. depardieui has evolved such an extreme method of escaping, while other wasps with similar lifestyles haven't.  "Maybe there is something peculiar about the host or where it lives," says Quicke. For instance, the caterpillar might make its home inside a leaf, which would be hard to break out of.  Other Rogadinae have evolved in different ways to escape their hosts. "Some... have quite bulbous faces, which might also be used to push their way out," says Quicke. Alternatively, the parent wasps might use these facial weapons to push into the caterpillars' homes.
The newly-discovered insect has a large ridge in the middle of its face, which it might use to rip caterpillars open