Data on the efficacy of deltamethrin flea control with small rodents on prairie dog colonies in Montana and Utah, 2001-2004. Data were collected on 12 colonies of 3 prairie dog (PD) species at 5 sites in Montana and Utah. PD species included black-tailed PDs (Cynomys ludovicianus, BTPDs), Utah PDs (C. parvidens, UPDs), and white-tailed PDs (C. leucurus, WTPDs). Sample sizes from 6 small rodents (Species in the data file) were sufficient for analysis: deer mice, grasshopper mice, Ord’s kangaroo rats, hispid pocket mice, dark kangaroo mice, and sagebrush voles. Efficacy of deltamethrin was assessed by combing fleas from live-trapped, anesthetized rodents on paired dusted and non-dusted plots (binary variable for DeltamethrinDust in the data file) in split colonies or separate adjacent colonies. Sampling of fleas occurred simultaneously on paired plots, thereby controlling for flea phenology when comparing flea parasitism on dusted and non-dusted plots. Each rodent was anesthetized with isoflurane and combed for 30 seconds (s) to remove fleas. During sampling of small rodents, >1 flea was found in only 5% of cases. No fleas were found in 88% of cases. Thus, we concentrated on indices of flea prevalence (FleaPrev in the data file) defined as detection or non-detection of at least 1 flea (binary 0/1).