Spotted Tiger Moth
Unlike L. argentata the caterpillar of this species feeds on a wide variety of broad-leaved trees and shrubs, and its distribution is by no means restricted to the West. Willow and Alder are its usual foodplants, but I have found them on Amelanchier, Rosa and Rubus among others. While the caterpillars of argentata are to be found in winter and spring, those of maculata appear in summer and fall. The typical full-grown caterpillar has the middle four segments brown, and the end segments black with numerous longer white hairs. There is much variation, however, and one of the illustrations shows one that is entirely brownish-yellow. The earlier instars are quite different, having the central segments bright yellow with a red line along the back, the end segments being black. The caterpillar pupates for the winter in a cocoon made from silk and hairs from the final larval instar. I have heard this moth called the "Spotted Tussock Moth", but it is not at all related to the true tussock moths, which belong to the family Lymantriidae.