True facts about army ants and their associates

December 17, 2020 • 2:30 pm

ZeFrank’s videos are getting better and better as he adds more biology, talks to experts in the field, and puts in professional videos taken by biologists. This one, about army ants, is especially good. Ants are strange anyway, but army ants, which have no permanent nests (often living in vans down by the river), are among the weirdest ants. We have them in the U.S., too, though you don’t often see them and they’re being extirpated by imported fire ants.

There’s a new book out on army ants (click on screenshot below), and though I haven’t read it, my ant friends (not ants, but people who work on them) say it’s excellent and especially well written.

As I said, army ants have no permanent nests, and are always on the move, though they move in a punctuated fashion, sometimes staying put for a while, but never living underground. Each nest has a single queen, and if that queen is killed by predators or dies, the nest is a goner, for the colony simply can’t function, plus it loses the only individual who can produce new ants. Male ants (drones) do no work, but march with the colony, and when it’s time to reproduce they fly away (they have wings) and find virgin queens in another nest.

Besides the reproductive queen, there are a few non-mated queens in each nest, and those come about when workers “decide” to give a few larvae extra food (probably richer food, too, as is done with “royal jelly” in bees). Those female larvae, coming from fertilized eggs (males, as in all Hymenoptera, develop from unfertilized eggs), become queens, and, when they’re ready to mate, emit a pheromone. That pheromone attracts the winged drones from other swarms, who fly to the other swarm and mate with the virgin queens, dying soon thereafter.

This produces an army-ant swarm with more than one queen, and that’s an intolerable situation for the workers. Thus such swarms undergo fission, with the newly-mated queens taking off with a bunch of workers to found their own swarm.  As with bees, the male ants are true drones, doing no foraging and serving only to contribute sperm to unfertlized queens.

One other note: Army ant queens are huge compared to workers, and would make tasty prey for a bird or other predator. That’s why, when the colony is on the move, the queen is surrounded by a retinue of workers, especially the soldiers with their fearsome jaws. Look at this size difference! (This is Eciton burchellii, a neotropical species in the genus most featured by ZeFrank):

Source. Photo by Daniel Kronauer

Here’s a pinned soldier of the species. Look at those jaws!

AntWeb.org image

The queen can lay up to 100,000 eggs in 20 days, and that’s why she needs that huge abdomen.

Here’s a fascinating Attenborough video on army ants:

26 thoughts on “True facts about army ants and their associates”

  2. I was very excited to see this video the other day and thought maybe Friday it will be featured here – especially because of that fascinating post about the ant catenary – or “antenary”!

  4. “often living in vans down by the river” – I don’t understand and Wikipedia’s “Van (disambiguation)” and “Vans (disambiguation)” didn’t help …

      1. That’s great! And now I get Mike’s comment at #1…

        I’ve always had an aversion to soldier/army ants after reading “Leiningen Versus the Ants” at an early age. (Somehow, I later found the film based on it, The Naked Jungle, amusing rather than scary, though.)

      3. Come on, we know you really DO have loads of ant friends!

        By the way, I did not enjoy it, but an ant features in Love & Other Thought Experiments by Sophie Ward… we read as part of the Royal Institution Fiction Lab where we read novels that contain science/scientists but are not science fiction. Previous book was Taylor’s Real Life which was much better, & features a good chapter on lab rivalry.

        1. “Come on, we know you really DO have loads of ant friends!” – one of them could be Dec, but could you tell?

  6. Interesting! I’ve recommended the book to my elibrary. Favorite new phrase- “ant death spiral.”

    1. “ant death spiral.”

      That part was completely fascinating – how sometimes they can break the behavior pattern. What’s more is the time lapse lets us see it happening in plain sight. Excellent application of video… and the branching attack structure-

      The video is also edited to perfection – no millisecond of dead view time.

  7. I’m hesitating to watch the army ant videos. I saw something on TV as a kid that made me awfully happy that I did not live in a part of the world where I could get overwhelmed and consumed by almost mindless tiny predators.

    By the way, I missed the postings on the day the tool use in bees article went up. I went back and read the article today, and I’m wondering if the dung has the same organic compounds as the plants they smear on the entryways to ward off wasps. Pandas apparently roll in dung to lather their fur in plant compounds that make them less sensitive to cold, so maybe something analogous is working with the bees?

    OK, maybe I’ll click ‘play’ now. I do love his videos!

  12. Thanks for the ZeFrank post; he’s always good.

    Tom Waits has a “song” (more of a spoken word piece) called “Army Ants” about many insect oddities:

    https://www.youtube.com/watch?v=lBkyaJqQ-50

    The song is mostly factual, ,and it contains the line:

    “and, as we discussed last semester, the army ants will leave nothing but your bones”

    Pretty much the same line appears in his “Earth Died Screaming.” Army ants appeal to him, apparently.

    And speaking of ants, since my granddaughter was born 10 months ago, we refer to my sister as La Gran Hormiga, a bilingual pun meaning “great ant.”

  13. I enjoy Ze Frank’s videos. This one was one of the most fascinating. I am going to put it on my facebook page. Too good not to share.

  14. I’d like to see more of the Ants v Wasps stuff at the end of the Attenborough clip, that was a bit of a tease.

    That’s the Aliens v Predator of the insect world.

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