Harvester ants are fascinating social insects known for their diligent seed-gathering habits. These ants, typically reddish to dark brown and ranging from 4.5 to 13 millimeters in length, establish complex underground nests in open, often arid, environments. Their colonies can grow to include thousands of individuals, forming intricate networks of tunnels and chambers. A common question arises about how these organized communities manage the remains of their deceased members.
Do Harvester Ants Eat Their Dead?
Harvester ants do not consume their dead colony members. Necrophagy, the consumption of dead individuals, is avoided by these ants and most other ant species. While some ants are carnivorous and may scavenge on other dead insects, they typically do not feed on their own kind within the colony.
The practice of eating deceased individuals could introduce pathogens or parasites back into the colony. Instead, ants have evolved specific behaviors to manage dead bodies. This approach helps maintain a healthy and sanitary environment for the living ants.
What Harvester Ants Do With Their Deceased
Harvester ants exhibit a specialized behavior called necrophoresis, which involves removing dead colony members from the nest. When an ant dies, its nestmates carry the body out. This ensures decaying remains are not left inside the living spaces.
The deceased ants are transported to designated areas, often called “graveyards” or “middens.” These refuse piles are located away from the main nest, sometimes as external dumps or in specific chambers. This waste management is common among many social insect species, highlighting their communal hygiene.
The Science Behind Their Sanitation Habits
The systematic removal of dead ants is driven by the need for disease prevention and colony hygiene. Decaying bodies can become breeding grounds for harmful bacteria and fungi, posing a significant threat to the entire colony’s health. By promptly isolating and removing these remains, ants reduce the risk of pathogen spread.
Ants recognize dead nestmates through specific chemical cues. A key signal is oleic acid, a fatty acid released as an ant’s body begins to decompose. When live ants detect oleic acid, it triggers the necrophoric response, prompting them to carry the “dead” individual away.
Live ants possess other chemical compounds on their exoskeletons that act as “life signals,” masking underlying death cues. These masking chemicals dissipate rapidly once an ant dies. The disappearance of these life signals then unmasks the oleic acid, signaling to nestmates that the individual is deceased and requires removal. Experiments show that if oleic acid is applied to a live ant, its nestmates perceive it as dead and carry it to the refuse pile, demonstrating the powerful influence of these chemical cues. This quick recognition and removal, often within an hour of death, maintains a clean and healthy environment.