The caterpillars of the silverspotted tiger moth feed on the needles, often "tenting" branches with dirty-looking webs. Feeding occurs through fall and winter, with webs becoming more noticeable by spring. The caterpillars can reach 1 1/2" in length and are mostly reddish-brown with some blue-black or yellowish hairs. Adult moths are brownish or tan with distinct silver-white spots on the wings. Minor infestations cause little harm to trees. Douglas fir is the preferred host, but the caterpillars will infest other conifers. Caterpillar hairs can cause skin irritation if they are handled without gloves.