"They're ants that collect skulls"

Discover:

For 60 years, scientists observing Formica archboldi, a species of ant native to Florida, have documented something…odd. The ants’ underground nests are littered with skulls and other body parts, primarily of Odontomachus, trap-jaw ants. Trap-jaws are formidable predatory badasses. F. archboldi are not. So what’s going on?

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To test what advantage this might provide, and to figure out if it explained the whole deal with the Odontomachus heads piled up in the skull collectors’ nests, Smith built a kind of ant Thunderdome.

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Smith found that in 1 out of 10 contests, F. pallidefulva successfully bested the trap-jaw ant, which was unable to walk around the arena afterward but was not fully immobilized.

The stats were a little different for F. archboldi, however: In 10 out of 10 contests, the trap-jaw ant was unable to walk around the arena and, in 7 of those 10 matches, the trap-jaw was completely immobilized.

If you’re imagining ants ripping each other apart, hang on. That’s not what the contests were about. Both Formica species use formic spray to immobilize prey and also as a defense.