Queens of some ant species have evolved an unusually hostile mode for colony takeover: they infiltrate colonies of other ant species and manipulate the worker ants into killing their own queen — their mother — then accepting the intruding queen as their new leader, according to a recent study.
In the world of ants, where battles over territory and resources are common, this is a rare example of matricide, or “the killing of a mother by her own genetic offspring,” researchers say.
The researchers observed such matricide-inducing behavior in two parasitic ant species: Lasius orientalis and Lasius umbratus.
Ants rely mainly on chemical signals to communicate and tell friends and foes apart. The parasitic queens of L. orientalis and L. umbratus use that to their advantage.
“Ants live in the world of odors,” Keizo Takasuka, study co-author from Kyushu University, Japan, said in a statement. “Before infiltrating the nest, the parasitic queen stealthily acquires the colony’s odor on her body from workers walking outside so that she is not recognized as the enemy.”
Once inside the colony, the parasitic queen covertly approaches the resident queen and sprays her with abdominal fluid that the researchers suspect is formic acid.
“When they get attacked, ants often spray the intruder with formic acid as a way of alerting other ants in the colony,” Daniel Kronauer, a researcher of insect societies at Rockefeller University, U.S., who wasn’t involved in the study, told Live Science. “So, it makes a lot of sense that this would be repurposed by the parasite queen.”
After spraying the host queen, the parasitic queen quickly retreats, letting the worker ants attack their acid-covered queen. “She knows the odor of formic acid is very dangerous, because if host workers perceive the odor they would immediately attack her as well,” Takasuka said.
Once the host queen is dead, the parasitic queen begins laying her own eggs, and the existing workers care for them, saving her the trouble of starting her own colony from scratch.
By doing so, the parasite queen “can use all the resources that are already in place and get her own colony up and running much faster,” Rachelle Adams, an evolutionary biologist at Ohio State University, U.S., who wasn’t involved in the study, told The New York Times.
Scientists have previously observed parasitic queens killing a host queen by throttling or beheading her. But this study is the first to document a new kind of host manipulation, in which offspring are induced to kill “an otherwise indispensable mother,” the researchers write.
The research team now plans to study if such matricidal behavior extends to insects other than ants.
Matricidal manipulation by the Lasius orientalis queen. Video by Takasuka et al., 2025 (CC BY 4.0).
Banner image: Parasitic ant queen Lasius orientalis, left, approaches the queen of L. flavus to spray her with a fluid. Image by Takasuka et al., 2025 (CC BY 4.0).
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