http://www.sciencemag.org/news/2019/08/slow-motion-video-reveals-how-ants-deliver-their-painful-venom

Painful encounters with ants don’t stem from their bite; it’s their venom-delivering stingers. Now, in a video posted online this week, a researcher has recorded the first ever close-up look at how these stingers work.

Ant stingers are slimmer than the width of a human hair. After biting down on their target to secure themselves, the insects swing their abdomens forward to get their stingers in place. Not all species have stingers (some spray toxic acid), but the feature—passed down from an ancient wasp ancestor—is more common than not.