Many fleas are quite host specific, although rodent and shrew fleas are occasionally also found on their predators, probably hopping on the nearest warm body when their host is killed. Fleas of the genus Nearctopsylla are primarily found on shrews and moles, but N. brooksi has so far only been reported from weasels (Mustela spp.). It is unlikely to be a weasel parasite so the true host has yet to be discovered. The flea in the photo was found on…you guessed it…a long-tailed weasel.
Contributed by Mike Kinsella.