The term "harvester ants" cover a rather large group of ants of several genus/species. Any of the harvester ant species are good food items for horned lizards. Carpenter ants and termites are also good food items for horned lizards. I can "rattle" off numerous "harvester ants" genus names and that would probably be even more confusing. Pogonomyrmex, a genus name, are the most common of the "harvester ants." They can be found throughout the southwestern United States and Mexico. There are also Messor, Camponotus, Myrmecocystus, Crematogastor, Dorymyrmex, Forelius, Pheidole, Solenopsis (not S. invicta, the non native fire ant), and many other ant genus/species that HLs will eat. The term "harvester ant" means that the ants harvest seeds for their own food source. That is the "short" version of "harvester ants," the horned lizard's main dietary requirement. Lester G. Milroy III