This spiny black and red caterpillar grows to approximately 2 1/4 inches in length. It is all black with red spots on the top of each segment and vertical rows of tiny white dots. The spines are long and black with short side branches.
The caterpillars can be seen feeding on leaves of willow, cottonwoods, elms and hackberries in late spring and early summer.
The larvae remain together feeding until they are ready to pupate. They can defoliate branches and small trees. The adult butterfly has a wingspan of 2 7/8 – 3 3/8 inches. Dorsally, its dark brown to maroon coloration has a velvety appearance. The forewing has pale yellow margins and 2 short vertical, yellow lines on the leading edge. Both wings have a row of blue spots above the yellow margin. Ventrally, both wings are striated chocolate brown with tan margins, and have a row of blue chevrons just above the margins.
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