Kelly didn’t notice this moth’s neatly grouped eggs until after reviewing her photos; a very exciting discovery! Large Yellow Underwings are named for their bright orangish-yellow hindwings decked with a narrow, black outer band and orangish-yellow fringe. The hindwings are covered at rest, but revealed if the moth is disturbed or in flight. These moths are native to Eurasia but were accidentally introduced to Nova Scotia in the late 1970s. Strong fliers, they dispersed, and have since spread north to the Arctic Ocean, west to the Pacific, and south to the Gulf of Mexico. They are now one of the most common moth species in many habitats.
The larvae, commonly called Winter Cutworms, are generalists that feed at night on many kinds of grasses and herbaceous vegetation. They feed into the fall, and even in the winter on warmer days (in the 40s). If you see a caterpillar crawling on the snow this is likely it! A portion of the larval population enters winter as last-instars (pupating in early spring) and the remainder enter as earlier instars (continuing to feed in spring). With the late date of egg-laying, we believe the presumed hatchlings are in the latter group. Larvae do have the potential to be a pest in both agricultural and urban areas, with a documented outbreak in Michigan.
Photos by Kelly Dix 10/9/20 in Lolo, MT