The dark reddish-brown caterpillar, unusually, has many of the same dark reddish brown colours of the adult. I have found it feeding on willow as well as on the flowers or leaves of Rosa nutkana, Rubus spectabilis and Rubus parviflora. These are doubtless not its only foods, for caterpillars of this genus have, in the words of Richard South, "a keen appetite for other caterpillars when the opportunity offers". Being a vegetarian myself, I have not offered tristigmata an opportunity, and it seems to survive quite happily. In fact the caterpillars are quite easy to rear, since only a short time is spent as a pupa, and the adult moth emerges in the fall. The adult overwinters, and is often one of the first moths to be seen in early spring or late winter. The orange dot in the forewing is accompanied by two additional satellite dots, accounting for the same "satellite" given to moths of this genus.