When polygyne forms invade areas where colonies have not yet been established, the diversity of native arthropods and vertebrates declines greatly. This is evident as populations of isopods, mites and tumblebug scarabs decline significantly. They can also significantly alter the populations of many fly and beetle families, including: Calliphoridae, Histeridae, Muscidae, Sarcophagidae, Silphidae, and Staphylinidae. Despite this, one review found that certain insects may be unaffected by red imported fire ants; for example, the density of isopods decreases in red imported fire ant infested areas, but crickets of the genus "Gryllus" are unaffected. There are some cases where the diversity of certain insect and arthropod species increase in areas where red imported fire ants are present. Red imported fire ants are important predators on cave invertebrates, some of which are endangered species. This includes harvestmen, pseudoscorpions, spiders, ground