In many countries, stinging insects are the wildlife most likely to kill a human being. In the US, for example, ants, bees, and wasps kill more than a dozen people a year, usually because of allergic reactions to the stings. The honeybee is our most frequent killer.
But those attacks are mostly defensive. The imported red fire ant deserves special mention because it's the only insect in the US that preys on people. That's happened several times in nursing homes, where helpless elderly people were partly eaten by fire ants, not necessarily after being killed. Elsewhere in the world, other ant species have attacked infants and hospital patients.
The ants are the smallest predators of people.