Dipodomys  

During the period extending from February 1955 to January 1956, 192 specimens of deer mice, Peromyscus maniculatus sonoriensis (LeConte), 174 specimens of white tail antelope ground squirrels, Citellus leucurus leucurus (Merriam) and 154 specimens of Ord kangaroo rats, Dipodomys ordii pallidus (Durrant & Setzer), were examined to determine louse-host associations, rate of infestation, frequency of distribution and seasonal fluctuation of louse populations.Five species of lice were recovered from three species of rodents. The dominant species on the deer mouse was Hoplopleura hesperomydis (Osborn). The dominant species on the white tail antelope ground squirrel was Neohaematopinus citellinus Ferris. The only louse species recovered from the Ord kangaroo rat was Fahrenholzia pinnata K. & F.Infestation on rodents was recorded on the basis of percentage of hosts infested, number of lice per host and number of lice per infested host. The highest number of lice per host was 27·7 Neohaematopinus citellinus per infested white tail antelope ground squirrel. The lowest value was 2·5 Polyplax auricularis per infested deer mouse.Approximately 80 % of the rodent sample had less than 25 lice per host. This grouping accounted for about one-half of the total number of recovered lice.Seasonal fluctuations of louse populations on deer mice, white tail antelope ground squirrels and Ord kangaroo rats were studied over one complete year. There appeared to be some coincidence between rodent activity, temperature and louse populations.