Fleas of the Norway Rat in the Superior, Wisconsin, Harbor Area (Siphonaptera: Ceratophyllidae, Hystrichopsyllidae)

The occurrence of the fleas of the Norway rat, Rattus noruegicus (Berkenhout) was monitored in Superior, Wisconsin, for 12 months. A total of 441 fleas was recovered from 300 rat hosts. Nosopsyllus fasciatus (Bosc), the northern rat flea, was the most abundant species found (94.1%) while Ctenophthalmus pseudagyrtes pseudagyrtes Baker (5.4%) and Megabothris asio asio (Baker) (0.5%) were also present. The flea index was highest (4.8) in July and lowest (0.2) in February and March. Forty-four percent of the rats examined were infested.