Florida's most metal ant collects the skulls of dismembered enemies to decorate nest

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Add Formica archboldi ants to the rotating cast of Florida creatures haunting your nightmares.

The state's most metal ant tricks a powerful species known as trap-jaw ants by chemically mimicking them and then spraying these enemy ants with immobilizing formic acid, according to new research by Adrian Smith, a scientist at North Carolina State University.

After the gruesome murders, F. archiboldi ants drag victims into their nest, dismember the bodies and collect the decapitated skulls to adorn their home.



For decades, previous scientists observed trap-jaw ant skulls in the nests of F. archiboldi ants, but thought that F. archiboldi ants had moved into abandoned former trap-jaw nesting sites where body parts are naturally found. The real reason behind the amassed carcasses was a lot more macabre, according to the study.

"In 1958, shortly after this ant was described as a species, scientists reported something weird about it," Smith said in a statement. "This was a study that grew out of reading a peculiar observation in a 60-year-old research paper. Odds were that these ant heads weren’t in Formica nests by chance and that there was some interesting biology behind this natural history note."

PHOTO BY ADRIAN SMITH
Smith's research was published last week in the journal Insectes Sociaux. To conduct the study, Smith used high-speed and time-lapse video recordings to observe the ants and record the interior nest chambers of laboratory colonies. Smith told The Verge that after F. archiboldi ants dragged a trap-jaw ant into the nest, they would "start licking it, biting it, moving it around on the ground like they would with food."

It's not clear yet if F. archiboldi ants are actually eating their enemies, though. Smith believes they may be feeding on trap-jaw ants because some body parts found in the nest are "cracked open and totally empty," Smith told The Verge.

"The scientifically surprising finding of this study was that these ants chemically match or mimic the chemical profiles of two species of trap-jaw ant," Smith said. "It’s really unusual for an ant species to display this much variation in chemical signature. Also, chemical mimicry is usually a tactic used by social parasites, but there’s no evidence that [F. archiboldi ants] are a parasitic species."

The study proves F. archiboldi ants are "the most chemically diverse ant species we know of," and the chemical mimicry further suggest the ant species likely have a long evolutionary history together, Smith argued

"Before this work, it was just a species with a weird head-collecting habit," Smith said. "Now we have what might be a model species for understanding the evolution of chemical diversification and mimicry."

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