Great Plains Natural Science Society


Date of this Version


Document Type



The Prairie Naturalist 47:13–20; 2015


Published by the Great Plains Natural Science Society. Used by permission.


We studied prevalence of bot fly infestation of thirteen-lined ground squirrels (Ictidomys tridecemlineatus) trapped during 13 years of population monitoring in shrub and grassland habitats in northern Colorado. We also investigated effects of prescribed burning, a common habitat management practice in grasslands, on bot fly prevalence. Infested squirrels were rarely located on shrub sites and during spring (May–Jun) trapping. Across all summers, mean prevalence in grasslands was 7.9% (range: 2.1–23.8%), with years of highest prevalence corresponding to years when the fewest hosts were captured in spring. Infested squirrels had from one to seven warbles, with 46.7% having only one warble. Prevalence did not vary significantly with host sex, age, or body weight. Prevalence was significantly higher (31.6%) in burned sites one year after a prescribed fire and tended to remain higher on burned than on unburned sites. Our results indicate that fires may alter the grassland environment in ways that increase the susceptibility of squirrels to bot fly infestation or the ability of flies to infest hosts.