Big bad ants

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July 10, 2013

Who are the big bad boys in the ant world? When it comes to size, none are bigger than the greater giant hunting ant (Dinoponera

gigantea). This monster of an ant — on record as being the largest ant in the world (Hermann et al. 1984) ­— measures about 1.5 in., is found in South America, primarily in the Amazon basin region; but  has spread to other areas such as the Andean foothills, south to Paraguay and through the Brazilian highlands to the Atlantic Ocean. Fortunately, it hasn’t made its way north into Central or North America. And by the way, it can sting. More on that in a bit.

But the baddest boy that gets my vote is the lesser giant hunting ant (Paraponera clavata), also known as the bullet ant, which measures about an inch long. Bullet ants are closely associated with trees. The South American oil tree (Pentaclethra macroloba) seems to be one of their favorites.

While in the trees, these ants have been known to drop onto perceived threats from vertebrate animals, including humans, and deliver a nasty sting, which is reportedly the most painful in the insect world — comparably to the pain of a gunshot, thus leading to the ant’s common name. They’re aggressive defenders of the nest and will take down small vertebrates, ants of different species and even ants of their own species from different colonies.

The bullet ant isn’t alone when delivering a painful sting. In 1984, Dr. Justin Schmidt, research director of the Southwestern Biological Institute, developed a pain rating scale (revised in 1990) to describe the various amount of pain associated with the sting from common bad boys. On the Schmidt scale, 1 is mild, and 4 is severe. The bullet ant is given a 4+ on the scale. To compare, check out Schmidt’s chart from the Encyclopedia of Insects (left).

Not only is pain associated with these insects, they’re also lethal. Looking at the lethal dose (LD) information of these insects, the amount of venom needed to kill a mouse is low for some. The harvester ant is the most lethal at 0.125 mg of venom per kilogram of body weight. The bull ant is 0.18 mg per kg. The cicada killer and tarantula hawk aren’t nearly as bad at 46 and 65 mg per kg, respectively. The bullet ant is 1.5 mg per kg.

The other issue that makes these ants the bad boys in the insect world is the duration of the pain. The burning pain as the result of a bullet ant sting can last for as long as two days. I’ve spent some time looking at bullet ants in the wild, and can boast I’ve never been stung by one, so I’ll have to take them at their word. pmp

You can reach Meek, international technical and training director for Orkin, at fmeek@rollins.com

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