"A. atropos" has a wingspan of 10 to 13 cm (3.9 to 5.1 in). The top wings are mainly dark brown or black. They are powdered with white. There are many black and dark red stripes. There is a small white spot in the center of each top wing. The bottom wing is yellow or yellow-brown. There are two black lines near the edge of each wing. The head and thorax are dark brown or black. They are the same color as the top wings. On the thorax, there is a dark brown spot that looks like a human skull. This is where the moth gets its name. However, some individuals do not have this spot. The abdomen is blackish-blue. There are is a row of yellow spots on each side of the abdomen.