Excerpt: While food plants of many species of sphinx moth larvae are well known, food plants of the adults are not. Many observations of the feeding habits of adult sphinx moths undoubtedly have been made, but much of the information is probably resting in the field notebooks and memories of the observers.
To my knowledge no summary of known feeding information has been presented previously for American Sphingidae. A rather thorough list of food plants for adult European sphinx moths has been published by Wahlgren (1941). This list also includes other moth families as well and it can be a useful reference for many workers.
Fleming, Richard C.
"Food Plants of Some Adult Sphinx Moths (Lepidoptera: Sphingidae),"
The Great Lakes Entomologist, vol 3
Available at: https://scholar.valpo.edu/tgle/vol3/iss1/2