Our largest tiger moth, each forewing with a span of 2.6-2.9 cm. It is known from western Oregon to southern California and the Channel Islands, east to Arizona, New Mexico, south into Mexico. The wings are lightly scaled with tan, especially the tips, making them translucent (thus the name glassywing). Older adults are often missing most of the scales and the wing tips become ragged. The head and thorax are clothed in fine tan hairs, the abdomen bright red-orange (easily seen through the translucent wings). They fly in a single brood from August to October, both sexes attracted to light (white, black [=UV], and mercury vapor). Eggs are laid on oaks, primarily coast live oak (Quercus agrifolia in our area). The caterpillars are brown-black with long hairs. Pupation takes place on or near the oak tree host, in a loose cocoon that includes hair from the caterpillar (as in many other tiger moths).
Caspers Wilderness Park, drawn to white lights at entrance booth. 30 September 2010. Photo and text by Bob Allen.
Reference: Powell, J.A. & P.A. Opler. 2009. Moths of Western North America. University of California Press, Berkeley, CA. Page 273, plate 48.23.