You can't. They are not commercially available. In any case, you will not need to purchase them because the natural enemies are expected to spread on their own. It would also be too expensive for the typical homeowner to purchase the natural enemies, even if the enemies were commercially available. For example, it costs several thousand dollars to get a decapitating fly population started in a particular area. Phorid flies, or decapitating flies, and Thelohania, a protozoan, have been released in most Southern states to determine if they will have an impact on fire ant populations. These natural enemies have spread rapidly from the point of release. For more information, see FAQ #855: "What can we expect from decapitating (phorid) flies?"