 And here's why. Frank's lab experiments show that without amputation, infection from the open wound will spread and almost always be fatal. Interestingly, however, amputation is only life-saving when the injury is in the upper part of the leg. And the ants seem to know that. Because when the wound is lowered down, they won't amputate. Instead, they spend more time licking and tending the damaged area, presumably treating it with antibiotic compounds.