Ants are social insects of the family Formicidae and, along with the related wasps and bees, ants belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than 12,500 out of an estimated total of 22,000 species of ants have been classified. Ants are easily identified by their elbowed antennae and a distinctive node-like structure that forms a slender waist.