The striped caterpillar that is crawling along the surface of fresh snow is the larval stage of a noctuid or owlet moth (species unknown). Noctuids are dull-colored, medium-sized, nocturnal moths that are attracted to lights in the summer. They usually possess a well-developed proboscis (mouthpart) for sucking nectar. You may be familiar with the common garden pests, cutworms, which are also noctuid larvae. How this larva survives freezing temperatures I do not know, but I have seen several dozen at a time crawling around on top of the snow. Note: Jean Harrison, a fellow nature lover, just identified this larva as Noctua pronuba, a winter cutworm also known as the greater yellow underwing (moth), a recent immigrant from Europe.
If you pull apart a red, fuzzy seed head of Staghorn Sumac (Rhus typhina) this time of year, you will find, in addition to a multitude of seeds, a profusion of scat in the shape of miniscule round, grey balls. If you’re lucky, you’ll find the larval insect that produced this scat. Chances are, according to Charley Eisman, author of Tracks and Sign of Insects, that many of the resident insects are in the Gelechioidea family of moths. The larvae of these moths are consumers of Staghorn Sumac seeds, and judging from the amount of scat usually present, they spend a considerable amount of time inhabiting the seed heads. It’s likely that Black-capped Chickadees and other birds you see gleaning sumac fruit are actually there for the larvae as much as the seeds.
The white-marked tussock moth caterpillar is brightly colored, with tufts of hair-like “setae.” As you might guess, it’s in the same family (Arctiidae) as the woolly bear/Isabella tiger moth. Although these caterpillars are appealing to the eye (of some people), it’s best not touch them, as their hairs break off very easily and can cause a painful reaction on your skin. There are a number of species of tussock moths, many of which, in their larval stage, have these bristles and tufts. As adult moths, most are brown or grey, and live long enough to mate, but they do not eat.