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Two evenings ago, Andrew called me out to the driveway – “I’ve got your next Natural Wonders for you!” he said. Sure enough, something weird was happening.

Our bridge was covered in red ants. Like, hundreds of them were crawling every which way, some with purpose, others wandering confusedly back and forth. Many of them were carrying eggs.

Blurry pic of a fast-moving ant - photo by Heather Wall

Andrew traced their path over the bridge, up the hill, through the gate and around the curve about 200-300 yards away – they were going back and forth between these two spots:

As we paid closer attention, it seemed the egg-carrying ants were more purposeful, carrying the eggs from the base of the tree over the bridge and up the hill. The other ones were coming back down the hill empty-handed.

Was this a case of ants moving their nest for some reason? Or were they raiding another nest?

By this time, it was starting to get dark but we stayed squatted down near the nest the eggs were coming from. And that’s when we saw one solitary black ant fighting among a group of red ants.

Now it began to look more like the red ants were raiding the black ants’ nest. This one black ant was the only one left – the solitary hero making a final stand, sacrificing himself (herself?) in a fruitless attempt to protect the eggs as the red ants carried them off.

The drama!

I know Henry David Thoreau wrote about a battle between red and black ants in his book “Walden, or Life in the Woods” published in 1854. Seven years before the start of the Civil War he wrote of the two warring factions of ants:

I should not have wondered by this time to find that they had their respective musical bands stationed on some eminent [wood] chip, and playing their national airs the while, to excite the slow and cheer the dying combatants. I was myself excited somewhat even as if they had been men. The more you think of it, the less the difference.

Obviously, individual animals will attack another to protect their young or to hunt for their next meal. But I hadn’t thought of an entire group of animals attacking another group – you don’t hear of this with schools of fish or flocks of birds, right? It’s something I thought was specific to us humans. But after seeing the hundreds (thousands?) of red ants carrying competitor’s eggs back to their nest, I wondered:

Do ants go to war?

What I found out was, honestly, one of the weirder things I’ve come across in the past few months of working on this newsletter.

The red ants we observed were kidnapper ants stealing the black ant pupae in order to enslave them.

The red ants, most likely a type of Formica ant, regularly raid nests of other ant species in order to steal the pupae right before they hatch into work-ready ants. These enslaved black ants will then live amongst the red ants and become their future workers for their entire 1-3 year lifespans. They will gather food, protect the kidnapper’s eggs, and even protect the nest as if it’s their own.

A kidnapper ant grooms a young captive ant, coating it in the kidnappers' nest signature smell. (Josh Cassidy/KQED)

In order to make sure the kidnapped ants remain in their new nest once they hatch, they have to be brainwashed into thinking they belong. So, the kidnapper coats the captured ant with chemicals it keeps in a pouch in the corner of its mouth. These chemicals are the unique scent for that particular colony that tell ants who bump antenna they are part of the same group. The enslaved ants are covered in the chemicals from the beginning and never know they’ve been kidnapped from a different colony.

In some subspecies, the black ants are taught to feed their kidnappers by regurgitating food into their mouths. It’s a process called trophallaxis and is fairly common in ants. What’s weird about regurgitation with the enslaved ants is that it’s the only way the kidnappers can survive – their mandibles (jaws) are great for carrying objects (like pupae) and for stabbing holes in enemy ants’ exoskeletons, but they don’t have the serrated edges needed to eat. They rely completely on the slaves to feed them through regurgitation – otherwise they would starve.

A captive ant regurgitates food into its captor's mouth. (Josh Cassidy/KQED)

Scientists are trying to understand how these ants evolved to become kidnappers. It’s obviously a survival technique that is working for the red ants. And while it freaks me out a bit to consider it, I realize I’m anthropomorphizing the situation and painting it in human terms. Ants probably don’t have enough emotional sophistication to realize they’ve become enslaved.

It just confirms that nature is fascinating and fluid and above all, functional. “Nature, red in tooth and claw,” as Lord Tennyson said.

What are your thoughts on this? Are you as bothered by ant enslavement as I am? Have you ever come across a swarming ant battle before? Join the conversation in the comments below:

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Nature break: Spend a few moments studying a one foot by one foot square of earth. Look for any movement to see if you can find any insect life. See any ants? Where are they headed? Can you determine their purpose? Are they working alone or as a team with other insects?

Weird Nature:

Not long ago, I wrote about Crows and their unique ability to communicate. Watch these two ravens, cousins of crows, and their synchronized flying:

Science girl @gunsnrosesgirl3

Ravens partner for life, monogamous and forming families these two know each other extremely well, look at their synchronised flight, dancing with identical pirouettes

Detritus

Thanks to reader Laura who alerted me to the Bearded Vulture, an Old World scavenger vulture that has a tiny little beard under its beak and survives almost exclusively on the bones of dead animals.
If you ever wanted to see a 3D molten aluminum casting of what an ant colony looks like, check out this Anthill Art video of how one is made.
Update on poison ivy: a couple weeks ago I wrote about poison ivy and mentioned that I’d gotten into poison ivy but was taking some pills to counteract the effects. I didn’t get a rash, so I stopped taking the pills about 4 days after exposure - and promptly got just a few itchy bumps. Then last week I got into quite a bit of poison ivy and wasn’t able to wash it off for about 10 hours, so I started taking the pills. I broke out into a slight rash, but it was manageable - until I used up all my pills. In the 2 days I’ve been waiting on my next batch of pills, the itching has been much worse. I’m thinking there might be something to these pills. Consider this a Public Service Announcement for those of you who are highly allergic. This was a cheap, simple solution that seems to work well for me!

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