Researchers have discovered how a parasitic ant species infiltrates host colonies by manipulating workers to eliminate their own queen. The invader uses chemical camouflage and a targeted spray to incite the attack, securing its takeover. This behavior, observed in Lasius orientalis ants, highlights sophisticated parasitic strategies in insects.
A team led by Keizo Takasuka at Kyushu University in Fukuoka, Japan, uncovered the mechanism behind the parasitism of Lasius orientalis queens on Lasius flavus colonies. When a Lasius orientalis queen is introduced to a host nest, she first cloaks herself in the scent of the colony's workers to bypass defenses. Many parasitic queens are killed upon discovery, but this camouflage allows infiltration.
Once inside, the parasitic queen sprays the host queen with a chemical, believed to be formic acid, from an orifice at her abdomen's tip. The workers perceive this as a threat to the colony and attack their own queen. The process unfolds slowly, requiring multiple sprays and repeated assaults before the host queen dies.
With the rival eliminated, the Lasius orientalis queen lays her eggs, which the workers then care for, effectively usurping the colony. Around 230 ant species exhibit parasitism, often by killing host queens or stealing brood to co-opt workers.
Takasuka compares the tactic to scenes in the television series The Walking Dead, where characters use camouflage to evade zombies: “It’s reminiscent of the zombie television series, The Walking Dead, where characters smear themselves with walker blood to pass through a horde — it involves camouflage that often fails, and those who are exposed are killed brutally.”
This strategy enables the parasite to skip the risky founding phase of a new colony. Takasuka suggests it may be more common than realized: “If the parasitism succeeds, it allows the new queen to pass through the vulnerable founding phase far more safely than founding a colony alone.”
Chris Reid at Macquarie University in Sydney, Australia, praises the research for revealing hidden ant behaviors in underground nests. “This kind of natural history detective work is vital for improving our understanding of these super important insects,” Reid says. He notes potential applications in controlling invasive ant species, a major ecological threat.
The findings appear in Current Biology (DOI: 10.1016/j.cub.2025.09.037).