Entomological Etymology: raider ants
Look at this mass of ants and their larvae. A happy little ant village, wouldn’t you agree? How nice.
But these ants have a dark side. These are raider ants. Raiders, you see, are pillagers like the vikings, like pirates. These baby ants are fed through invading the nests of other ants. Because the larvae demand, above all else... flesh.
It all begins with ants on scouting duty.
Though blind, these ants wander outside the nest, exploring with their antennae, which are full of intricate chemical and touch sensing cells.
Sooner or later, the scouts encounter something intriguing: a pupa from another ant species, in this case Tetramorium, or pavement ants. The scout spends a while investigating the pupa, tapping it all over, checking if it could be a healthy meal for her sisters back home in the nest.
Eventually, she decides that yes, this is a good one. Now, she returns home to let everyone know. Along the way, she lays an invisible pheromone trail marking the path between nest and food.
Back at the nest, the scout emits a puff of another type of pheromone, drawing the attention of many of her sisters. These other ants drop what they are doing, and are drawn toward the source. This is called recruitment. These workers all join together in what’s called a “raiding party”. We think this amounts to a show of force: together, these ants could fight off any defenders in the prey nest. The raiders follow the trail pheromone back to the food.
Encountering no resistance, the raid will conclude with the ants dragging the food pieces back to the nest. They will be devoured by the hungry larvae and workers.
To be clear: predatory behavior is natural and normal. I don’t fault these ants in the slightest for their way of life. In fact, I have frequently aided and abetted their hunger, when I personally dug up hundreds of fire ant colonies to collect pupae to feed to little baby raider ants.
Since fire ants are a destructive pest species in the US, I didn’t feel bad about it either. That’s Solenopsis invicta, by the way. Solenopsis means something like “the appearance of a pipe”, which I do not understand. Invicta, on the other hand, means invincible, and makes perfect sense with their nasty sting and incredible ability to rally a defense. Still, they can be defeated with long socks, a shovel, and a bucket.
I don’t endorse projecting human cultural ideas onto animals. They’re just living their lives in a way that works for them. But I do think that ant group raids are neat. The word “raid” was chosen because it’s evocative and descriptive of how the ants find food, but these ants could just as easily have been named for something else. For instance, their scientific name tells another story. They’re part of genus Ooceraea, which comes from Greek words “oo-” for egg and “ceraea” for antenna. In other words, the ants with egg-shaped antennae, named for the distinctive final antennomere, or antennal segment.
These ants are cousins of the so-called “army ants”. They are all part of the Doryline sub-family, which you might call the “spear ants” from Greek “dory”. Army ants are called as such because Europeans who described them likened them to a military on the move, as they march in long lines by the hundreds of thousands. The raider ants are smaller, and have much lower populations, but raider ants and army ants share a taste for insect flesh, and the ability to work together to find food and overwhelm defenders. Other bugs run at the sight, if they know what’s good for them...
Words: raider ant, Ooceraea, Doryline, army ant, antennomere.
Sources:
Chandra et al., 2021. PNAS.
George Wheeler, 1956. Myrmecological Orthoepy and Onomatology.
