The Costa Rican Army

Costa Rica is a peaceful country (also a tiny country, less than half the size of Pennsylvania), and it hasn’t had an army since 1949. It abolished the army because of a bloody civil war, and now tourism (especially ecotourism) makes more revenue than the country’s top three exports combined (bananas, pineapple, coffee) (source: Wikipedia).

As many ticos will tell you however, they do have an army of sorts…just not a human one.

Meet the Costa Rican army (Eciton burchellii I think):
Costa Rica
Workers communicating with each other…my favourite (fictional) short story about army ants is Leiningen vs the Ants. Read it here!*

One of the most interesting things about army ants is that they don’t form a physical nest, like most ants or social bees. Instead, they are nomadic, and when they want to stay in one place, they form a nest out of the living members of their hive, called a bivouac.

Costa Rica
Can you spot the soldier? One of the characteristics of a eusocial species, like this one, is caste differentiation. The morphology of the soldier and worker castes is very different because they specialize on different jobs.
Costa Rica
Good relative size comparison…the soldier is at the top. I heard a talk recently where the speaker said jaw muscles make up something like 65% of the space in an ant’s head.
Costa Rica
Porters are another caste, smaller than soldiers. You can see them carrying insect prey
Costa Rica
Look at those massive mandibles

*Upon rereading this classic short story I realize it has its share of offensive phrases and misinformation (tapirs aren’t predators, what? did the writer ever go to Brasil? also, army ants don’t cut down vegetation, that’s leaf cutters), it’s still really well written and fun to read.

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4 thoughts on “The Costa Rican Army

  1. Amazing details. How close did you get to the ants to take these photos? Was there a risk that they might spray formic acid on you, or were they uninterested in what you were up to?

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