Parasitic matricide, ants chemically compel host workers to kill their own queen
Researchers detail a parasitic strategy, first observed in a blog post, where an invading ant queen uses a chemical spray to compel host workers into killing their own mother
Kyushu University
image:
Researchers report on a behavioral phenomenon where parasitic ants trick a host colony into killing its own queen. In this photo, the parasitic ant queen Lasius orientalis (left) infiltrates the nest of Lasius flavus and apporaches their queen (right). The parasite will then spray the host queen and trick the colony to attacking their own mother. Once the host queen is dispatched, the parasitic queen will take over.
view moreCredit: Keizo Takasuka/Kyushu University
Fukuoka, Japan—In the ruthless world of parasitic ants, taking over a host colony is a matter of life and death. The conventional understanding has been that an invading queen must physically fight and kill the resident queen to seize control. However, a new study published in Current Biology details a more sinister strategy: a parasitic ant queen that chemically manipulates the host colony’s workers into executing their own mother.
“The initial discovery was made by my friend Taku Shimada, the first author of the paper, who has been passionate about ants since childhood and runs a popular blog called ‘AntRoom.’ He observed the colony infiltration and posted about it in 2021,” explains Assistant Professor Keizo Takasuka of Kyushu University’s Faculty of Science, the corresponding author on the paper. “I found the post three years later and was so astonished. I thought it was a very valuable discovery that deserved to be documented as academic knowledge.”
The chemical manipulation was documented in two distantly related species of parasitic ants and their hosts: Lasius orientalis, which infiltrates the nests of Lasius flavus; and Lasius umbratus, which invades the colonies of Lasius japonicus.
“The parasitic behavior of the latter species of ants was discovered by Yuji Tanaka, who is the second author of this study. He is another enthusiastic amateur of ants and followed the same observational methods established by Shimada,” explains Takasuka.
In the case of Lasius orientalis, the parasite sprayed the host colony queen repeatedly, about 15 times over 20 hours. This slowly agitated the host workers, who began attacking their queen, eventually mutilating and killing her after four days.
The Lasius umbratus queen, however, used only two targeted sprays. This was enough to incite an immediate and fatal attack from the host workers, who proceeded to dismember their queen. In both cases, after the matricide, the host workers accepted the parasitic queen, who soon began laying her own eggs to be cared for by the orphaned colony.
The researchers suggest this fluid was formic acid, a well-known defensive compound used by many ant species to deter predators or as a warning signal to fellow nestmates. In this context, it appears to act as a deceptive social signal.
“In both cases, the host and parasite belong to the same genus, so they both have formic acid and recognize it as a danger signal,” states Takasuka. “We believe that when their queen is suddenly covered in a large amount of this chemical, the workers perceive their own mother as a colony-threatening crisis which triggers their aggressive defensive behavior.”
To get close enough to perform this manipulation, the parasite must first bypass the colony’s guards. The researchers replicated this step in their experiments through a process called host-odor pre-acquisition.
“Direct infiltration would fail because the workers would immediately perceive the intruder and attack her,” continues Takasuka. “To achieve this, the parasitic queen was housed with a few host workers and cocoons. After just one night, she acquired the host colony’s specific scent, providing a chemical camouflage that was essential for her to get past the initial defenses.”
Interestingly, even though these two parasitic ant species are not close relatives, they share the same genus that is known to have two discrete origins of social parasitism. Takasuka explains that these behaviors are an example of convergent evolution, where similar traits develop independently between unrelated species.
“My own research focuses on how parasitoid wasps manipulate the behavior of spiders, so I know that in the natural world, parasitic organisms utilize many various and interesting strategies to infect their hosts,” concludes Takasuka. “This discovery in ants is another fascinating example. I am interested in investigating these different host-killing strategies to understand the evolutionary pressures that drive them.”
A full video showing the ants and their behavior can be found here.
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For more information about this research, see "Socially parasitic ant queens chemically induce queen-matricide in host workers," Taku Shimada, Yuji Tanaka, Keizo Takasuka, Current Biology, https://doi.org/10.1016/j.cub.2025.09.037
Journal
Current Biology
Method of Research
Experimental study
Subject of Research
Animals
Article Title
Socially parasitic ant queens chemically induce queen-matricide in host workers
Article Publication Date
17-Nov-2025
Parasitic ant tricks workers into killing their queen, then takes the throne
Cell Press
video:
Unwitting matricidal ants
view moreCredit: Current Biology / Takasuka et al.
Scientists document a new form of host manipulation where an invading, parasitic ant queen “tricks” ant workers into killing their queen mother. The invading ant integrates herself into the nest by pretending to be a member of the colony, then sprays the host queen with fluid that causes her daughters to turn against her. The parasitic queen then usurps the throne, having the workers serve her instead as the new queen regent. This work appears in the Cell Press journal Current Biology on November 17.
“At first, I wanted the title of this study to exemplify a fable where a daughter is tricked to kill their mother. I asked CHATGPT if this kind of matricide appears in a fictional story, but it said no such story exists,” says lead author Keizo Takasuka of Kyushu University. “So, this is an example of nature going beyond what we’ve seen in fiction.”
Matricide, a behavior where offspring kill or eat their mother, is a rarely seen phenomenon in nature. Despite appearing maladaptive at first glance, it does offer advantages by either nourishing the young and giving the mother indirect benefits through increased offspring survival or allowing the young to invest in offspring of their own. “Up until now, only two types of matricide have been recorded in which either the mother or offspring benefit. In this novel matricide that we reported, neither profit; only the parasitic third party,” says Takasuka.
The ants Lasius orientalis and umbratus, commonly referred to as the “bad-smell ants” in Japanese, are so-called “social parasites” that execute a covert operation to infiltrate and eventually take over the colony of their unsuspecting ant queen hosts, Lasius flavus and japonicus, respectively. The parasitic queen takes advantage of ants’ reliance on smell to identify both friends and foes to dupe unsuspecting worker ants into believing she is part of the family.
“Ants live in the world of odors,” says Takasuka. “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.”
Ant species taking over another’s colony using scent as cover is not a new phenomenon; there are many examples of ant social parasitism where, after entering a colony, a parasitic queen will directly kill the colony’s queen and convince the workers to serve her instead. There have even been prior reports of workers killing their queen in response to a social parasite’s presence, but only now have the actions that cause this matricidal behavior been observed.
Once these “bad-smell” ants have been accepted by the colony’s workers and locate the queen, the parasitic ant douses her with a foul-smelling chemical researchers presume to be formic acid—a chemical unique to some ants and stored in a specialized organ. “The parasitic ants exploit that ability to recognize odors, we believe, by spraying formic acid to disguise the queen’s normal scent with a repugnant one. This causes the daughters, who normally protected their queen mother, to attack her as an enemy,” Takasuka says.
Then, like fleeing the scene of the crime, the parasitic queen immediately (but temporarily) retreats. “She knows the odor of formic acid is very dangerous, because if host workers perceive the odor they would immediately attack her as well.”
She will periodically return and spray the queen multiple times until the workers have killed and disposed of their mother queen. Then, once the dust has settled, the parasitic ant queen returns and begins laying eggs of her own. With this newly accepted parasitic queen in the colony and no other queen to compete with, the matricidal workers begin taking care of her and her offspring instead.
Now that this kind of behavior has been captured on video, Takasuka and his research team will explore how far this unique form of matricide extends, and whether it can be found in other insects outside of ants. “Only ants in the subfamily Formicinae use formic acid to elicit violent responses, but I don’t rule out the possibility that non-formic-acidic ants and social wasps commit matricide in similar ways,” Takasuka says.
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This study was financially supported by the Sumitomo Foundation (2402610). The APC of this publication was supported by the Tokuo Fujii Research Fund.
Current Biology, Takasuka et al.: “Socially parasitic ant queens chemically induce queen-matricide in host workers” https://www.cell.com/current-biology/fulltext/S0960-9822(25)01207-2
Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit: http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.
Journal
Current Biology
Method of Research
Observational study
Subject of Research
Animals
Article Title
Socially parasitic ant queens chemically induce queen-matricide in host workers
Article Publication Date
17-Nov-2025
