To my eye the description of snowberry clearwing matches better. What are you seeing that makes you feel it's thysbe?

Hemaris diffinis
Adult: forewing clear area lacks partial crossband of dark scales near base; legs black; underside mostly black.

Hemaris thysbe
Adult: forewing clear area has partial crossband of dark scales near base, and distal margin of clear area is uneven or ragged-edged (not smooth-edged); legs pale/whitish (vs. reddish in gracilis and black in diffinis). Underside mostly white in front, extending to front legs, then reddish behind, unlike mostly black underside of H. diffinis.