The Abbott’s Sphinx caterpillar starts out green in the 1st instars with a horn on the last segment (A8). The middle instars are whitish to blue-green with faint, dark cross-stripes and the horn is replaced by a raised, orange knob on A8. The last instars may be brown with a wood-grain pattern or brown with 10 pale green saddles along the back. In late instars the knob resembles an eye. The prolegs are banded black and white. It grows to approximately 3 inches long. The adult moth has a wingspan of 2.5 to 2.75 inches. The forewing is violet gray to dark brown and has barklike pattern. The outer margin is deeply scalloped. The hindwing has a broad yellow basal patch. The abdomen is short and wide with a brushy three-pronged tip.