This close to one inch horse fly looks almost pettable, with its creamy hair, but better to err on the side of caution. Females, like this one, feed on the blood of warm-blooded vertebrates, with slashing-sponging mouthparts making for a painful bite. Merrill Peterson, author of Pacific Northwest Insects, notes that this species “Occasionally bites people but prefers livestock.” Males have a smaller pale area than the females, and solely visit flowers. The aquatic larvae live in mud at the waterline of lakes, ponds, streams, ditches, and marshes. True to its western name, this species is widely distributed and abundant from British Columbia to Kansas, south to California, Mexico, Texas, and Oklahoma. 

Photo by: Lisa Ann Cloo on 7/22/21 in Clinton, MT