Blackburn's Sphinx Moth is Hawaii's largest native insect, with a wing span of up to 5 inches (12 centimeters). Like other sphinx moths, it has long, narrow forewings and a thick, spindle shaped body tapered at both ends. It is grayish brown in color with black bands across the top margins of the hindwings and five orange spots along each side of the abdomen. The large caterpillars occur in two color morphs, bright green or gray with scattered white speckles throughout the back and a horizontal white stripe on the side margin of each segment. In its larval stage, the Blackburn's sphinx moth is a 3.5- to 4-inch (9- to 10-centimeter) caterpillar.