Answer to the Monday Night Mystery

What was that inexplicable bit of chitin hiding away in a hole in a twig?

This photo should help:

It’s the heavily sclerotized head shield of a Cephalotes varians turtle ant. Ants in this mostly Neotropical genus inhabit pre-existing cavities in trees and branches, a limiting resource that spurs intense competition among colonies of various tree-dwelling species. Workers come in two size classes: small and relatively lithe, and tank-like with a dinner plate for a head.


Turtle ants aren’t fighters. Rather, they’re all about defense. If a colony gets hold of an old beetle burrow, the heavily armored majors will plug the entrance with their head shield and sit tight, budging only to let their nestmates pass. They are literally living doors.


As usual, the commentariat picked this one within minutes. Points are awarded as follows:

  • 8 points for JasonC., who nailed the order, family, genus, and the behavior.
  • 2 points for MarekB, who picked the species
  • 2 bonus points for James Trager, who submitted a fine tall tale about diptera that made me laugh

As a word of thanks, I borrowed the ants over the weekend from Corrie Moreau, an ant specialist at the fabulous Chicago Field Museum. Corrie has been studying the surprising endosymbionts of these beautiful insects. I’ll be posting more about turtle ants later in the week.


  1. #1 Comrade PhysioProf
    April 13, 2010

    That’s definitely the first time I’ve ever encountered the phrase “I borrowed the ants over the weekend”. FTW!

  2. #2 Alex Wild
    April 13, 2010

    It beats renting the ants, that’s for sure.

  3. #3 JasonC.
    April 13, 2010

    Aw, I already miss WordPress! How do you like ScienceBlogs so far? (Personally, all the ads on the side really distract from the insect photos, but that’s my problem).

  4. #4 Tom
    April 14, 2010

    excellent pics as always. I envy that MPE-65 of yours. I just posted some images of a queen-ant. Do check it out if you have time (

  5. #5 Adrian Thysse
    April 14, 2010

    The turtle ants…love the last photo.

    With hats like that, I do wonder if these can do the gliding act as well. I don’t suppose you dropped one…?

  6. #6 Karen
    April 15, 2010

    As ever, I am in awe of your photographs. This is fast becoming my favourite blog.

  7. #7 Monado, FCD
    April 15, 2010

    Ads in the side? What ads? I have AdBlock. There are no ads to trouble me.

    You’re right! I assumed that the head shields were convex, but there’s definitely a Necker-cube perception flicker between convex and concave.

  8. #8 alex brown
    April 19, 2010

    I have a collection of Cephalotes in Dominican and Chiapas amber which match your turtle ants – great photography.

  9. #9 tim
    April 22, 2010

    I never knew these were also called turtle ants, they remind me of that dinosaur, triceraotops with out the horns maybe?!?

  10. Every photo is so WOW.I love to scroll it up-n-down so many times.Very Nice.

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