Hemaris gracilis is distinguished from similar species by a pair of red-brown bands on the sides of the thorax, which varies from green to yellow-green dorsally and sometimes brown with white underneath. They have a red abdomen. The wings are transparent with reddish brown borders. The outer edge of the forewing transparent area is even and the forewing cell has a median row of scales. Also note the red coloration on dorsal surface of legs. Hemaris gracilis, Peterborough, Ontario, May 30, 2007, courtesy of Tim Dyson.

Note the red-brown bands on the underside of the thorax, and the red upper surfaces of the legs. In a slightly larger species, Hemaris thysbe, the underside of the thorax lacks the red-brown bands, and the upper surfaces of the legs are off-white. Also in H. thysbe, the outer edge of the forewing transparent area is irregular with red-brown projections emanating from the outer margin, particularly at mid wing.

Hemaris gracilis, Peterborough, Ontario, May 30, 2007, courtesy of Tim Dyson.

Hemaris gracilis, Peterborough, Ontario, May 30, 2007, courtesy of Tim Dyson.