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Northland Nature: Watching cold-weather moths

Retired teacher Larry Weber, a Barnum resident, is the author of several books, including “Butterflies of the North Woods,” “Spiders of the North Woods,” “Webwood” and “In a Patch of Goldenrods.” Contact him via Katie Rohman at krohman@duluthnews.com.

A spanworm — a type of winter moth — as seen on the surface of the snow in November. (Photo by Larry Weber)

Early November is usually a time of "AutWin" — after the leaf drop of October and before lasting snow cover. But this year, AutWin was shortened a great deal. We had barely a week between the leaf drop (Oct. 12) and what appeared to be a lasting snow cover (Oct. 20). This could change with recent mild weather.

I expect when I walk in the woods at this time to see plenty of mosses, clubmosses and ferns that are still green among the brown fallen leaves. Though a few trees — ironwood and some sugar maples and red oaks — have not shed their brown leaves, nearly all the rest have. A few willows in swamps and lingering tamaracks have retained their yellows, but mostly what I see during my walk today is bare trees and a snow-covered scene.

The day is cloudy and calm with chilly temperatures in the twenties. Instead of looking at the forest floor and seeing some greens, I’m looking at the tracks of local critters that tell of their activity, mostly at night.

Deer tracks and trails reveal stories of their wandering and at many locations, they have been digging among the fallen leaves in search of acorns that were so abundant this year. They are joined by local turkeys also scratching in the leaves. Fox and coyote tracks go about the woods, too, to seek prey. Squirrels, hares and mice that could become their prey have been moving actively.

Raccoons and bears that will be sleeping in the deeper cold are still moving, trying to satisfy omnivorous diets. Their tracks show travels into a variety of places, one of which is near a beaver pond where the owner of the lodge comes ashore for more twigs before the freeze-up. We don’t usually see beaver tracks in snow. This is a bit of a surprising find, but not like the one that I see next.


As I wander during one of the woods walks, I see some flitting in the air. I pause to watch and I realize that I am observing the flight of a moth. After some of the cold that we’ve had, snow cover and ice on a nearby pond, it seems almost surreal to see this critter. Looking more closely, I recognize this insect as a “winter moth." This flight is not of a confused or displaced individual. This is their regular flying time.

Spanworms — a mostly gray-colored winter moth — are attracted by light and often seen on house windows and headlights. (Photo by Larry Weber)

The name of "winter moth" may be applied to a couple of late-season moths. Two in particular that I see often in late October or early November are the spanworm and the basswood (linden) looper. Both are small with wingspans of less than 1.5 inches. Spanworms are mostly gray; loopers are brown. Each can be very cryptic among the present trees.

They are common in the late-season woods, but also frequently seen on windows of our houses, attracted by the indoor lights, or maybe noted in the headlights of our cars as we commute home. I see the spanworm today.

Flying at a late date is a bit strange for these moths, but they have adapted. With little food available, they do not eat. After seeking shelter under bark, they shiver to warm the body temperature in order to fly. With fewer bird predators in early November, the flying males can locate females. This flight time is a bit unusual, but the spanworm that I watched on this chilly day, is also part of the woods community.


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Larry Weber
Larry Weber

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Retired teacher Larry Weber, a Barnum resident, is the author of several books.
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