Among the most damaging pest ant species is Solenopsis invicta, a fire ant native to South America. This species has been accidentally imported to the southern United States, eastern Australia, China, and elsewhere. Here a worker fire ant is shown in stereotypical defensive posture, her sting extruded, waving a droplet of venom in the air. Austin, Texas, USA

Her nest disturbed by the photographer, a Solenopsis thief ant worker exudes a droplet of venom on her stinger and waves it in the air. This behavior is known as "gaster-flagging". Morretes, Paraná, Brazil

Nylanderia sp. recruiting in large numbers to an insect carcass. Cape York Peninsula, Queensland, Australia