Erynnis tristis, the mournful duskywing, is a species of spread-wing skipper in the butterfly family Hesperiidae. It is found in Central America, North America, and South America. It is mottled brown with a white fringe on the hind wings. It appears similar to the funereal duskywing, but the mournful duskywing is more likely to appear in urban areas. The larva feed on young oaks while adults nectar from a variety of wild and garden flowers. The MONA or Hodges number for Erynnis tristis is 3953.