Can an Ant Queen Take Over a Rival Colony Using a Chemical Weapon?

The Short Answer

Yes — researchers have documented two ant species in which a rival queen physically approaches the resident queen, sprays her with a chemical thought to be formic acid, and causes the colony’s own workers to turn on and kill their queen before accepting the intruder as their new ruler.

What Scientists Actually Observed

In a finding described as the first of its kind, scientists watched an invading ant queen walk directly into an established colony, locate the resident queen, and deliver multiple close-range jets of abdominal fluid onto her body. The behavior was deliberate and targeted — this was not a chance encounter. Within moments, something remarkable happened: the colony’s own workers, the same individuals born to protect their queen, attacked and killed her. The intruder was then accepted without resistance as the new queen.

This was observed in two separate ant species, which suggests the strategy may not be an isolated quirk but a broader evolutionary tool that science is only beginning to uncover.

How Formic Acid Makes the Betrayal Possible

The chemical at the center of this coup is believed to be formic acid, a compound that ants produce in a venom gland located inside their abdomen. What makes this weapon so extraordinary is its precision. The formic acid does not harm the workers at all. Instead, it appears to reprogram their behavior — essentially overriding their loyalty and redirecting their aggression toward the very queen they were genetically primed to defend.

The mechanism is a form of chemical deception at a level of sophistication that researchers say has never been documented before in any ant species. The workers are not acting against their instincts in any conscious sense. They are simply responding to chemical signals, and the invading queen has learned — through millions of years of evolution — exactly which signal to send.

The History Behind Formic Acid

Formic acid takes its name from the Latin word for ant — formica. It is not a recently discovered compound. Naturalists first isolated it in 1671 by distilling large quantities of red ants, making ants one of the earliest subjects of chemical extraction in scientific history. The fact that this same ancient compound may be the key to one of the most sophisticated hostile takeovers in the animal kingdom is a remarkable full-circle moment for entomology.

What Happens After the Takeover

Once the resident queen is removed, the colony does not collapse. It keeps running. The invading queen begins laying her own eggs, and over time her offspring gradually replace every original worker in the colony. The structure remains intact. The routines continue. But the entire genetic lineage of the colony has been quietly and completely replaced — an invisible hostile takeover with no reconstruction required.

Why This Discovery Matters

There are an estimated 20,000 ant species on Earth, and the vast majority of their social behaviors remain unstudied in any depth. If two species have independently evolved this chemical strategy — or share it through common ancestry — the likelihood that others use similar tactics is significant. Researchers are now asking how many ant coups have gone undetected simply because no one thought to look for them. The insect world may be running political operations that dwarf anything we have catalogued so far.