We collected fleas from colonies of black-tailed prairie dogs in Badlands National Park, South Dakota, 2020-2021. Specifically, we tested fipronil grain for flea control on two colonies: Colony A in 2020 and Colony B in 2021. To assess on-host flea numbers (in 2020 and 2021), we anesthetized trapped prairie dogs (and their fleas) with isoflurane in induction chambers for processing. We combed each individual with a fine-tooth comb for 30 seconds to remove and count fleas. We released all animals, after they were recovered from anesthesia, at the location where they were captured. To assess off-host flea numbers (in 2021), we used a plumber’s cable to insert a 20- by 20-centimeter flannel-cloth as deep as possible into burrow tunnels. We then shook the cable for 30 seconds to imitate movement by a host. We removed the cloth from the burrow and counted detected fleas. Total flea counts from individual prairie dogs or burrows were considered an index of flea abundance. The first data set (Fleas 2020.csv) includes data from captures and combings of individual prairie dogs in 2020 and the second data set (Fleas 2021.csv) includes data from captures and combings of individual prairie dogs and swabbing of individual burrows in 2021. Funding and logistical support were provided by the US Geological Survey; Prairie Wildlife Research; National Park Service; US Forest Service; and US Fish and Wildlife Service.