An Eciton hamatum soldier uses her ice-tong mandibles to latch on to the photographer's skin. This gives her the leverage to use her stinger (at the read end of the animal) and makes her very difficult to remove. http://www.alexanderwild.com/Ants/Taxonomic-List-of-Ant-Genera/Eciton/9383120_8pS7kf#!i=1183697635&k=oysde