American Dagger

The American dagger moth has a wingspan of 50 to 65 mm (2.0 to 2.6 in) It usually has a sharp, double postmedian line, with white in between the two lines. There is a black dash on the anal area of the forewing. The hindwing is gray with a faint, darker gray median line in the male. The female is similar, except the hindwing is completely dark.

The young caterpillar is densely covered with yellow setae. The older caterpillar's setae are either pale yellow or white. All instars have thin, black setae on the first and third abdominal segments. On the eighth abdominal segment, there is one tuft of black setae. The caterpillar will reach a length of 50 mm (2.0 in). While there are numerous reports of the larval hairs of this species sometimes causing skin irritation in humans, there is no evidence that they possess any form of venom.