These large moths are often mistaken for hummingbirds since their rapid wing movement resembles a hummer in flight (hovering over flowers while feeding). They usually fly at dusk, during the night, and at dawn, but can also be seen flying during the day. These moths are widespread and can be found throughout the United States. Their range extends north into southern and midwestern Canada and south into Central and South America.
Photo by Gwendolyn Gunn around 8/24/20 in Red Lodge, MT.