Orchopeas leucopus is a common flea, primarily associated with various Peromyscus spp. in eastern North America (Benton, 1980; Holland, 1985). It is frequently encountered throughout the year (e.g. Benton and Altmann, 1964; Jackson and DeFoliart, 1976) and has been collected from a large number of hosts, many of which are undoubtedly accidental: Didelphis, Sorex, Blarina, Glaucomys, Spermophilus, Tamias, Tamiasciurus, Sciurus, Sigmodon, Ondatra, Dipodomys, Perognathus, Neotoma, Onychomys, Reithrodontomys, Microtus, Clethrionomys, Synaptomys, Napaeozapus, Mus, Erethizon, and various carnivores (Morlan, 1955; Benton, 1980; Haddow et al., 1983; Holland, 1985). There is even a record of O. leucopus from the Saw-Whet Owl, Aegiolus acadicus (Holland, 1985). On June 15, 1989, while collecting bats from Brown's Cave, 2.2 mi. SW Evans, Douglas County, Missouri, a male O. leucopus was found on the back of an adult female Pipistrellus subflavus (RMP 2546). This record is the first from P. subflavus, or any Chiroptera, for that matter. It was almost certainly an accidental association, where a suitable host probably nested nearby, though no evidence of other small mammals were observed in the cave. The specimen of P. subflavus is deposited in the Texas Cooperative Wildlife Collection (TCWC). The specimen of O. leucopus is deposited in the J. B. Wallis Museum of Entomology, Department of Entomology, University of Manitoba, Winnipeg, Manitoba, Canada.