The seasonal population dynamics reflect the climate of central Pennsylvania in 2018 and 2020. There was an unusually large rainfall event in 2018 that negatively impacted horn fly reproduction, as noted in Smith and Steiman (2022). The manure treatments differed by year. In 2018 pastures were dragged with a vehicle-towed manure spreader, whereas in 2020 manure pats were smeared with a hand-held plaster spreading tool. Temperature and precipitation were recorded in the study pastures. Temperature represents air temperature (not manure temperature) at about 30 cm above the soil. In the published analysis, temperature and precipitation represented the seven day period after the pasture dragging event, when flies were likely to be in the larval stage. In 2018 temperature data were not available from the HOBO device for the first experiment round. In lieu of this we included publicly available weather data (from wunderground.com) from a weather station located about 2 miles from the study site.