Found on a road, posed. These caterpillars ofen reach near-plague proportions in my neighborhood in Durham, North Carolina. They are abundant on Water Oaks, Quercus nigra, and frequently almost defoliate them. Their frass gets everywhere--all over my deck, sidewalks, and car. One finds the mature caterpillars wandering around on roads, etc., in late August and into September.

Caterpillar pupated successfully and a female emerged the next summer, during daylight, immediately surrounded by males--shown in linked image.