Winter cutworm, Noctua pronuba

by Alan Eaton, UNH Cooperative Extension

wintercutworm

Winter cutworm

In January 2017, we received several reports (some with photos) of cutworms on top of the snow in New Hampshire yards and fields. They came from Hillsborough county and at least 3 towns in Cheshire county. Where did they come from? What is this new insect? Well… this isn’t completely new. Noctua pronuba is a species that is more commonly known as the “large yellow underwing”. The moths I’ve seen have an orange color on the underwing, but I didn’t get to name the species. It is known in Europe and other regions, as well as in North America. Larvae are typical cutworms. I’ve found them in my garden and elsewhere. The first larvae I saw were collected on UNH campus walkways and submitted to me perhaps 15 years ago. The larvae have been reported feeding on a wide range of herbaceous plant species in many families. They can tolerate pretty cold conditions, and can feed during mild periods in our winters, in addition to the normal growing season. My larval photo (above) is from February 2013. I thought: good ice fishing bait!

adult

Noctua pronuba adult

It is unusual to see caterpillars on top of the snow, but this species can do that. Finding themselves exposed, they soon burrow deeper (it takes a while, in the cold), unless a lucky bird finds them. People ask if this portends some new, significant pest problem. No, it shouldn’t. The larvae are subject to many of the same natural enemies as our other cutworms. We can find this cutworm in spring and fall too. In our insect collection, we have New Hampshire specimens (the moths) from as early as 1990. Our specimens before that were collected in Canada. The adults are strong fliers. This species could very well have spread here on its own.

The adults have variable coloring & pattern in the forewings, but the hind wings are bright yellowish-orange with a dark band at the edge. Growers asked me: is this the beginning of a new major problem? I doubt it. There are lots of predators & parasites that attack cutworms.

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