The Old World ant cricket Myrmecophilus americanus Saussure (Orthoptera, Myrmecophilidae) inhabits nests of the Old World tramp ant Paratrechina longicornis (Latreille) (Hymenoptera: Formicidae). Paratrechina longicornis has spread worldwide through human commerce, whereas M. americanus has been reported from sites in Asia, Oceania, South America, the West Indies, and the Mediterranean region. Here, we report the first North American records of M. americanus, all from peninsular Florida and the Florida Keys. In addition to older unpublished records of M. americanus from Archbold Biological Station (N 27.2°) and Gainesville (N 29.7°), we collected M. americanus from 5 of 13 P. longicornis nests surveyed in southernmost Florida (N 24.5–26.0°), but only from 1 of 20 P. longicornis nests surveyed further north (N 26.5–27.3°) in Florida. Although P. longicornis is common throughout most of Florida south of N 30°, its symbiont M. americanus appears to be common only in southernmost Florida. If climate limits populations of M. americanus in northern Florida, then it is likely that the higher latitude records reported as M. americanus from subtropical semi-arid Mediterranean sites (Egypt, Libya, and Israel; N 30–32°) are actually misidentifications of one or more distinct species, possibly Myrmecophilus cottami Chopard and/or Myrmecophilus surcoufi Chopard.