He was investigating a dying flower that also had aphid-like creatures. I believe he might be a soldier from Camponotus yogi, but I don't know enough about ant identification to be sure.
San Diego County, California, US
Mystery ant, large and small, see finger for scale.
Ants are social insects of the family Formicidae /fɔrˈmɪsɨdiː/ and, along with the related wasps and bees, 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 have been classified. They are easily identified by their elbowed antennae and a distinctive node-like structure that forms a slender...