The most infamous ant in the world is surely the tropical American bullet ant, Paraponera clavata. This conspicuous insect is known for an unusually painful sting. It is not the only big rainforest ant, however, and other species are frequently mistaken for it.
Here is how to make sure that big ant you saw was really a bullet ant.
1. Check your location: in the wild, bullet ants are only found in low-elevation forests from Honduras south to Paraguay. If you are not in Central or South America, you don’t have a bullet ant. (source)
2. Check the size: bullet ants are not just large, they are massive – over an inch long. They look like plastic toy ants brought to life.
3. Check for the characteristic thoracic horns. Bullet ants have a pair of blunt horns on the first segment of the thorax. No other ant its size has the horns.
4. Check the shape of the petiolar node. The waist of the bullet ant has a sharp, forward-leaning triangular node.
With these criteria in mind, here is a real bullet ant:
For comparison, these other large South American species are not bullet ants:
With any luck, you should now be able to check the identification of your purported bullet ant without having to run a sting test.