We collected fleas from a colony of black-tailed prairie dogs on Buffalo Gap National Grassland, South Dakota, 2021. We collected flea data by combing prairie dogs and swabbing their burrows for fleas. Regarding combing, 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. Regarding burrow swabbing, 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. Data were collected on four plots treated with lufenuron and nitenpyram "LN-Bit" bait pellets for systemic flea control with prairie dogs. Each LN-Bit contained 75 milligrams lufenuron and 6 milligrams nitenpyram. The LN-Bits were applied at 50 baits/acre on two plots (single treatments) and 100 baits/acre on two plots (two treatments separated by four weeks). The initial treatments were completed on 23 August 2021. The second application (on the latter two plots) was completed on 22 September 2021. Combing flea data were collected 2-21 August 2021 (before treatments) and 27 August–10 September 2021 (after initial treatments). Swabbing flea data were collected 15-17 August 2021 (before treatments) and 15-17 November 2021 (after initial treatments). The first data set (LNBit Combing Data.csv) includes data from captures and combings of individual prairie dogs and lists treatment (TREATMENT = LN50 [50 baits/acre once] or LN100 [100 baits/acre twice]), period of experiment (PERIOD = BEFORE [before treatments] or AFTER [after initial treatments]), and flea abundance (FLEAS). The second data set (LNBit Swabbing Data.csv) includes data from swabbing of individual burrrows and lists treatment (TREATMENT = LN50 [50 baits/acre once] or LN100 [100 baits/acre twice]), period of experiment (PERIOD = BEFORE [before treatments] or AFTER [after initial treatments]), and flea abundance (FLEAS).