Labidus coecus, masters of the underground

If Eciton burchellii receives a disproportionately large share of scrutiny, here’s an army ant that suffers the converse fate of chronic inattention:

Labidus coecus (Ecuador)

Labidus coecus was the first army ant I ever saw in the field.

A narrow column emerged briefly above ground and underfoot as I lined up to get vaccinations as a fresh Peace Corps trainee in Asuncion, Paraguay. The ants had a fetid odor I was not expecting and were as shiny as glass.

Labidus coecus is ubiquitous from southern Texas to northern Argentina and is a master of the underground realm. There’s a great deal I could write about it, but I’ll defer to the inimitable Jack Longino:

This is one of the most remarkable of all army ant species. It has an extremely broad ecological tolerance. It occurs across a great latitudinal range, from the equator to the subtropics of both North and South America. It occurs in dry forest and wet forest, in primary forest and in second growth, in coffee farms and pastures, and in suburban yards. It occurs from sea level to high montane regions. The highest ant record I have for Costa Rica, a collection at 3000m near Villa Mills, is Labidus coecus.

The species is almost entirely subterranean, sometimes at considerable depth…

…In the study of army ants, most of the attention has focused on the large epigaeus species in the genus Eciton. But the highest density and most ecologically important army ants may turn out to be L. coecus. Kaspari and O’Donnell (2003) have estimated that every square meter of rainforest floor may be visited nearly daily by army ants, largely due to high densities of L. coecus found in sample plots of rainforest leaf litter.


Removing surface soil reveals the subway system of Labidus coecus (Maquipucuna reserve, Ecuador)
workers rush to repair the damage

Contrast the efforts foisted on the conspicuous above-ground E. burchellii with that of the abundant, but secretively subterranean, Labidus coecus:

Google Scholar search returns for 4 common army ants.

Studies of an underground insect will be logistically difficult, of course, but L. coecus is surely an important enough animal to merit more research than it has received.

a worker guards a hole in the tunnel

[addendum: see Scott Powell’s excellent post on the frugivorous tendencies of this species.]

6 thoughts on “Labidus coecus, masters of the underground”

  1. Smooth as glass for sure – which brings up a question in my mind about the adaptive significance of surface sculpture in ants. Any ideas? I’m sure the extreme spininess of Atta and relatives has antipredation benefit, but what about glassy smoothness like this versus the intrictate ridges or heavily punctured superficie of most other ants?

    1. Doesn´t it seem to be highly sensible to be smooth as can be, if your main workload is managed underground? And one has to be swift and would want to avoid annoying tidbits hanging on?
      Just a very layman thought on a probably much more delicate subject, but I couldn´t stop myself asking…

    2. That’s a good question. I had the passing thought that smooth integument might just be hard for ant mandibles to grip- a useful trait when fighting- but I don’t really know. Some army ants are smooth, some are rough.

      There are several real actual army ant biologists who read this blog (namely, Gordon Snelling, Scott Powell, and Daniel Kronauer), perhaps one of them has some ideas.

  2. Labidus coecus is the army ant I collected in pitfall traps in my study sites in the Fort Worth Nature Center & Refuge, Fort Worth, Texas. I had just started learning ant taxonomy and identification. My eyes nearly bugged out of my head when I got her under the scope to identify! Formidable head and jaws, little abdomen, no eyes! I love this ant.

  3. Pingback: Army Ants: Reader Questions Answered, And Not Answered – MYRMECOS - Insect Photography - Insect Pictures

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