All ants came from one mother. When the queen lays eggs, her daughters, the worker ants, care for them with utmost devotion and pass down the same genes to the next generation. When a parasitic ant enters, the peace of ant society is shattered in an instant. The worker ants kill their mother and serve a fake queen that came from outside. As in the U.S. HBO drama Game of Thrones, vile schemes for the throne play out in real life.
A team led by Takasuka Keizo, a professor in the Department of Biology at Kyushu University in Japan, said, "We witnessed a scene of matricide in which a parasitic ant queen infiltrates, deceives the worker ants, and kills the real queen," in Current Biology on the 17th (local time). Later, the worker ants served the parasitic queen who had usurped the throne.
◇Usurping the throne by hacking ants' chemical signals
Commonly called "stink ants" in Japan, Lasius orientalis and Lasius umbratus are parasitic ants that stealthily infiltrate colonies of Lasius flavus and Lasius japonicus, respectively. Ants secrete pheromones, signaling hormones, to identify friend and foe, but fail to distinguish the parasitic ants. Professor Takasuka said, "Before infiltrating a colony, the parasitic queen ant smears on her body the pheromones secreted by host ants roaming outside so she is not recognized as an enemy."
Once the parasitic ant is accepted by the worker ants as a fellow, it begins a full-fledged usurpation of the throne. When the parasitic ant locates the queen, it sprays a foul-smelling chemical, presumed to be formic acid. Professor Takasuka explained, "By disguising the queen's normal scent as a repulsive odor, the parasitic ant exploits the ants' ability to perceive smells," adding, "The worker ants, the daughters who normally protected the queen, perceive her as an enemy and attack."
The parasitic ant temporarily hides from the crime scene. Exposure to formic acid could lead to it being attacked as well. The parasitic ant periodically returns and sprays the foul substance on the queen multiple times until the worker ants kill the queen and dispose of the body. Once the matricide scene is cleared, the parasitic queen returns and begins laying eggs. The worker ants begin caring for the parasitic ant that instigated the matricide and its offspring.
The title of the paper is "A parasitic ant queen elicits matricidal worker behavior through chemical manipulation." Professor Takasuka said, "At first, I wanted to make the paper's title like a fable in which a daughter is deceived into killing her mother and asked ChatGPT, but it replied that such a story does not exist," adding, "This result is an example of nature showing us more than what we have seen in novels."
Daniel Kronauer, a professor in the Department of Biology at Rockefeller University in the United States, told the New York Times, "It's like something out of Game of Thrones." Kronauer is a scientist who identified, at the genetic level, how ants communicate through smell and also revealed the mutation process by which a fake queen ant arises in an ant colony.
◇Triggering treason without stepping forward to avoid counterattacks
Matricide, in which offspring kill or eat their mother, is rare but does occur in nature. In some spider species, spiderlings grow by consuming the mother's body. At first glance it seems abnormal, but in fact it stems from an instinct to spread more offspring that share the same genes. But these ants are different. Professor Takasuka said, "In this case of matricide, neither the mother nor the offspring benefit; only a third party that parasitizes gains."
This is not the first time parasitic ants have hacked colony-specific scent information to infiltrate other ant groups. Of about 15,000 ant species, roughly 400 are known to be parasitic ants. Most secretly enter the homes of other species and parasitize them. Scientists believe ants that parasitize specific ant species evolved over thousands of years.
Typically, a parasitic queen ant invades another ant colony, directly kills the queen, and persuades the workers to serve her. This is the first time a process has been observed in which the parasitic queen does not stain her own hands with blood but induces matricidal behavior in the worker ants. Then why does the parasitic queen not simply kill the host queen directly and instead go through this cumbersome process of rebellion?
Christian Rabeling of the University of Hohenheim in Germany told Science that it is "because the strategy of directly killing the queen is extremely brutal." A parasitic ant chooses one of two methods: cutting off the queen's legs, wings, and antennae and then beheading her, or biting her neck and starving her to death. Both methods take time and can invite counterattacks from the workers protecting the queen. Rabeling said, "It is much safer to manipulate the daughter ants to do the dirty work."
The research team said it will investigate whether matricide appears in other insects in the future. Professor Takasuka said, "Only the subfamily Formicinae triggers violent reactions through formic acid, but we do not rule out the possibility that ants or social wasps that do not use it could commit matricide in a similar way."
◇An ant version of the film Parasite also exists
Parasitic ants do not come only from outside. There are also fakes inside that pose as queens. Kronauer of Rockefeller University reported in Current Biology in 2023 that in a species of clonal raider ant, a winged mutant worker loafed around and lived off its peers.
Raider ants invade other ant nests and steal eggs or larvae to use as food. The mutant worker ants grew wings like a queen. They shirked work as if they were real queens, received care from other workers, and lived comfortably.
To understand the behavior of the mutant ants, the researchers put only mutant ants in one nest and ordinary ants in another. When a scout found prey and returned home, all the ordinary workers came out and rushed to the prey. In contrast, the winged fake queen ants showed no reaction. Whether it is Game of Thrones or Parasite, stories for film or drama are abundant in nature.
References
Current Biology (2025), DOI: https://doi.org/10.1016/j.cub.2025.09.037
Current Biology (2023), DOI: https://doi.org/10.1016/j.cub.2023.01.067