Holoarctia sordida is a moth of the family Erebidae. It was described by McDunnough in 1921. It is found in the mountains of Alberta and British Columbia and possibly Yukon and Alaska. The habitat consists of dry rocky alpine tundra. The length of the forewings is 15–16 mm. The forewings are charcoal grey with pale yellowish lines. The wing margin is off-white. The hindwings are dark smoky grey with darker veins. Adults are on wing from July to mid-August.