This is a winged female of the famous Bullet Ant, which supposedly has the most powerful sting in the world. I tried to get my finger in the shot for scale without getting too close. These things were about an inch long, which is gigantic for an ant. We saw maybe a dozen or so during the trip, usually on tree trunks. You really have to be careful about brushing up against or leaning on any sort of vegetation with these things lurking around, but by far the most common and annoying ants were the Leafcutters, which covered pretty much every square foot of ground, making standing in one place for more than a few minutes a bad decision.