Tramp ants

I’ve talked about invasive ants before; in particular, I have talked about the nasty invasive fire ants (Solenopsis invicta), whose name means “invincible” or “unconquered”.  I studied those guys when I worked for a brief time with Walter Tschinkel at FSU.  (Good times, but lots of blisters from fire ant stings.)

But as vicious and well known as the fire ants are, they are not the only vicious invasive ant species.  There are in fact a number of ant species, known as “tramp ants”, that hitchhike on human transportation, establish readily, and spread widely. 

Here are a few other terrifying invasive ants.

Rasberry Crazy Ants (Nylanderia fulva) — The New York Times had a great (and terrifying) post about this a few days ago, including this beautiful photo.

Bill McCullough for The New York Times

Bill McCullough for The New York Times

So named for their erratic and even “psychotic” behaviour, the crazy ants are tiny, but numerous.  Millions of them infest homes in Texas, and they love electricity: televisions, laptops, cars…their known for shorting out all sorts of electrical systems.  Thus, they cause extensive damage and seem completely unstoppable.

The Yellow Crazy Ant (Anoplolepis gracilipes) — These guys are famous for the detrimental ecological impacts they are having on oceanic islands.  Specifically, they have a detrimental impact on native hermit crabs on Christmas Island (McNatty et al. 2009).

Yellow Crazy Ants dragging away a gecko, courtesy of

Yellow Crazy Ants dragging away a gecko, courtesy of

Why are they so detrimental?  Well, like other invaders, they spread quickly and are generalists, meaning they eat just about anything.  This means they outcompete with native species for food resources due to their abundance.

The Argentine Ant (Linepithema humile) — According to this awesome Radiolab episode, the Argentinian ant is vicious because it kills anything unfamiliar.  Like white supremacists, or any other racial purists, they do not interbreed and they do not mingle. There are lines of millions of dead ants where colonies meet.

Argentinian ant queen and worker, photo by the fabulous Alex Wild

Argentinian ant queen and worker, photo by the fabulous Alex Wild

This has resulted in the fascinating phenomenon of three “global colonies” of pure genetic descent from the original colonies introduced from Argentina.  They occupy Europe, North America, and Japan.  One colony stretches for more than 900km in California.

The Fire Ant (Solenopsis invicta) — I don’t feel like I need to say much about the invasive fire ant, the scourge of the south.  This ant is very noticeable because anyone who accidentally disturbs a mound is swarmed by thousands of ants whose stings leave white pustules on the skin.  I had an earlier post about some of their ecological impacts.

The Red Imported Fire Ant, photo by the fabulous Alex Wild

The Red Imported Fire Ant, photo by the fabulous Alex Wild

They are now distributed globally.  But they do have some good effects…for example, they inspired E. O. Wilson.

The Little Fire Ant (Wasmannia auropunctata) — Also known as the electric ant, this tiny little bugger actually has a pretty painful sting.  In spite of its diminutive size, in fact, the little fire ant can have extremely detrimental impacts on native species, such as the Galapagos tortoises (poor things are already having a hard time). 

The little fire ant, or electric ant, courtesy of

The little fire ant, or electric ant, source

The Bigheaded Ant (Pheidole megacephala)  —  So named because of the large heads and mandibles of the soldiers (which are about twice as large as the workers), the Bigheaded Ant is a prime example of how these introduced species can achieve competitive asymmetry through sheer abundance.  According to one study, this species was found to be “11–62 times greater in abundance than that of all native ants in uninfested sites, corresponding to a 4- to 18-fold increase in ant biomass” (Hoffmann and Parr 2008).

Comparing soldier (above) and worker (below), courtesy of

Comparing soldier (above) and worker (below), courtesy of

Though the ecological impacts are still unknown, the abundance and diversity of other invertebrates was found to be much lower in invaded sites.

Tramp ant impacts

Although individually very small, these tramp ants can have huge ecological and economic impacts, and the species listed are considered to be among the worst invaders worldwide.  The fact is that their ability to act as a colony makes them a serious threat.  They can spread rapidly, establish anywhere, and outcompete native species for resources.  (Sort of like humans, I guess.)

Hence the inspiration for the villains in Ender’s Game!

It's us or them, courtesy of

It’s us or them, courtesy of


9 thoughts on “Tramp ants

  1. We have the Argentine ant here in SF. They are horrendous. I’ve lost beehives to their super-colony populations.. They invade our house (are invading.. right.. now..). I’m so glad I can’t see how many are actually living inside our walls, because it would seriously disturb me!

  2. Little Fire ants. Yow! Last march in the Bahamas I paused on a sandy area by a remote pond to photograph a rarish bird (Sora, a furtive type of rail). I was so absorbed that I didn’t notice I’d inadvertently stood on a fire ant nest, with hilarious consequences. They are so small they are hard to track and dislodge (& they climb legs…quickly). I confirm what you say, that quite disproportionate to their size they can have an extremely detrimental impact, and not just on the Galapagos tortoises. Little bastards. RH

    • I’ve made the same mistake on a bull ant nest. *shudder* I also accidentally sat on a fire ant nest when I was three years old. My dad rushed me inside, put me in the bathtub and turned on the shower full blast to get them off.

      Soras are super cool though! Bet it was worth it.

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