A newly discovered wasp has been keeping a gruesome secret, it stuffs ant corpses into the walls of its home. As far as scientists know, the behavior is unique in the animal kingdom. The new creature has been named Deuteragenia ossarium, or the bone-house wasp, after the historical ossuaries piled high with human skeletons found in monasteries or graveyards.
“It was a totally unexpected discovery,” said Michael Staab, a researcher at the University of Freiburg in Germany.
The reason it fills a nest chamber with dead ants is even more surprising, baby proofing.
“Our discovery demonstrates in an impressive way, what fascinating strategies of offspring-protection have evolved in the animal kingdom,” said lead author Michael.
Here’s how this works: spider wasps build large nests usually constructed out of plant debris, soil and resin. Each nest contains several cells where the mother wasp lays her eggs. Once the nest is constructed and the eggs are laid, however, she abandons them, leaving them vulnerable to predators and parasites, such as parasitical wasps.
It builds a final outer layer cell around its brood in which it piles dead ants, sealing them up in a seeming bug-recreation. Yet the wasp doesn’t do this out of vengeance, but to better-safeguard its nest.
“We propose two non-exclusive hypotheses: chemical camouflage and chemical defense by utilization of volatile chemical cues emanating from the dead ants,” the authors write.
“In other words, even though they are dead, the ants still emit telltale chemical compounds. These compounds could potentially camouflage what’s really inside the nest, for example keeping parasitical wasps away. It could also scare away possible predators, since most ant species ferociously defend their colonies against intruders,” the scientists explain, who discovered the behavior in the tropical forests of China’s Gutianshan National Nature Reserve.
The most commonly found ant in these murder-cells is the Pachycondyla astuta, which the research call an aggressive, large-bodied, and common species in the study region that has a powerful sting.”
They hypothesize that the dead-house wasp targets this ant species not just because of its well-known ferocity, but also because of its abundance in the area. Potential nest-raiders have likely already had bad encounters with this particular ant species. Moreover, as this is a big ant, the wasp only needs a few individuals to fill its macabre cell.
The scientists found that the construction of the ant bone house is, indeed, an effective strategy. In the nests they inspected the researchers never found the parasitic wasps that commonly invade other nests. Instead, the bone house wasp’s nests were “only attacked by parasitoids which entered the nest prior to the construction of the ant chamber.”
Other wasp especially parasitic ones resort to similarly grisly measures to protect their offspring. The parasitic wasp Dinocampus coccinellae, for example, hijacks ladybug bodies, turning its victims into zombie slaves that keep predators away from its larvae.