Northern Prairie Wildlife Research Center
Yellow to waxy green, with variously developed reddish markings. Head somewhat flattened, held forward with red lateral stripes continued onto antennae and back onto thorax, intermittent on abdomen, again strong on anal proleg. Dorsum with dark dot at anterior edge of first 8 abdominal segments; these often bounded on either side by whitish patch that is edged with black and/or red. Legs often vinaceous. Pink-striped willow spanworm (C. variolaria), similar but with edging on white dorsal patches less pronounced. Food: willows and poplars. Caterpillar: May to October; 2 generations in North.