Ants exhibit many fascinating behaviors, including carrying their dead. This strategic practice is widespread among many ant species, serving important functions for the entire colony and highlighting their complex social organization.
Reasons for Carrying Dead Ants
The main reason ants carry their dead nestmates is colony hygiene and disease prevention. Ants live in densely populated, enclosed environments, which can become breeding grounds for pathogens. Dead ants, like any decomposing organic matter, quickly harbor bacteria, fungi, and other microorganisms that threaten the colony’s health. Removing these decaying bodies minimizes the risk of infection spreading.
Ants identify their dead through specific chemical signals. When an ant dies, its body releases fatty acids like oleic acid and linoleic acid as decomposition begins. These compounds act as “death pheromones,” signaling to other ants that a nestmate has perished and needs removal. Conversely, some research suggests that living ants continuously produce “life chemicals,” and the disappearance of these chemicals triggers removal in some species. This sophisticated chemical communication ensures healthy ants are not mistakenly carried away.
While the main purpose of removing dead ants is sanitation, ants are also opportunistic scavengers. They often collect other dead insects as a food source, providing essential nutrients for the nest. However, for their own kind, cleanliness is the priority, ensuring potentially contaminated bodies are removed from living quarters.
The Disposal Process
Once identified by chemical cues, specialized worker ants, sometimes called “undertaker ants,” transport the deceased. They pick up the dead ant with their mandibles and carry it away from the main nest. While the general method involves carrying or dragging, specific techniques can vary slightly among different ant species.
The destination for removed bodies is typically a designated waste area known as an ant “cemetery” or “midden.” These middens are refuse piles located outside the colony’s main living quarters, chosen to prevent contamination. Along with dead ants, these areas may contain other waste materials like discarded food and debris, all deposited to maintain a clean environment within the nest. Some ant species may even bury their dead within specific chambers.
Distinguishing between truly dead ants and those that might be stunned or inactive is important. If an ant is merely stunned, it may still emit life-indicating pheromones, or death-indicating chemicals may not yet be present, delaying or preventing its removal. Studies show applying death-signaling chemicals, like oleic acid, to a living ant can cause its nestmates to mistakenly carry it to the midden, highlighting the strong programmed response.