Western black carpenter ant (Camponotus modoc)
“Bring out your dead!”
If ever there was a moment for that epic Monty Python and the Holy Grail quote – this week’s Crawlies is it.
Pictured is a western black carpenter ant (Camponotus modoc) carrying the body of her dead sister.
With some species, this might be the set up for a good “Who done it?” Did one critter kill the other? Was it in a battle? What will they do with the body?
When it comes to ants, however, we already have all the answers because ants are very organized.
We know both ants are female because all worker ants are female. We also know both are “major” worker ants. Carpenter ant workers come in three sizes – minor, media and major. These ladies are wingless. Males are sized between minor and media. They have wings and they never leave the nest (unless the entire colony has to move due to some disaster or other).
Workers come in a variety of sizes because every ant in a colony has very specific duties. Some care for the queen; cleaning, feeding, etc. Some gather food for queen and colony, some care for the young and some guard the colony against enemies such as other ant species, termites, etc.
Then there are the few dedicated undertakers who quite literally bring out the dead. That is the job of our pictured Ms.
Whether an ant dies inside the colony or outside – such as in battle – undertaker ants will carry the body to the colony’s midden.
A midden is the ant equivalent of a mulch pile; it’s where the colony disposes of all their waste, including their dead. Middens can be inside a colony, in a special separate chamber, or outside.
The process of carrying the dead out of the main colony is called “necroptosis” from the Greek nekros meaning “dead body.” It’s a savvy habit as removing the dead prevents the spread of disease and/or fungus.
In some ant species this threat is taken so seriously that undertaker ants practice social distancing from all other members of the colony, sometimes even living just outside the colony in case they picked up any disease or bacteria from their corpse removing duty.
In most colonies any worker ant can and will move a corpse to the midden when necessary, but it’s the undertaker ants’ specialty.
Ants will also retrieve their dead from outside the colony; those who die in battle, are squished, or predated upon. Ants know a corpse left unretrieved can lead danger back to the colony itself.
Undertaker ants find their dead by using their antennae to sniff out oleic acid. This is a pheromone emitted when ants die. To be more precise, it’s emitted when they are alive too, but they also emit other pheromones colony members use for other purposes. When ants die, the other pheromones cease to be produced, and only oleic acid remains.
Ants don’t retrieve just their dead, however. These highly social animals strictly adhere to the practice of “No ant left behind.”
Colony members wounded in battle or while out foraging will be carried back to the colony by their sisters. Once safely home, other workers will tend to their wounds and feed them until they heal.