Lethal myiasis of Richardson's ground squirrels by the sarcophagid fly Neobellieria citellivora

Larvae of the sarcophagid fly Neobellieria (formerly = Sarcophaga) citellivora caused lethal cutaneous myiasis in Richardson's ground squirrels from late June through September in southern Alberta, Canada. Of squirrels resident in mid-June during the 3-year study, 8.6% of 348 juveniles eventually were parasitized by N. citellivora, whereas only 1.0% of 197 adults were parasitized. Among juveniles, 13.0% of 154 males and 5.2% of 194 females were parasitized. Age- and sex-specific differences in time of entry into hibernation accounted for this differential vulnerability of squirrels to parasitism. Squirrels usually were infested with >80 larvae, and frequently with >200 larvae, resulting in massive tissue damage and subsequent death.