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Northland Nature: Woolybear caterpillars seek shelters now

A woolybear caterpillar as it appears while crossing the road in early November, seeking food and a shelter for winter. Photo by Larry Weber

The woods of early November is open and reveals conditions of the autumn interlude — between leaves dropping from trees and the lasting snow cover.

This is a remarkable time, almost a season of its own, and I like to refer to it as "AutWin." It may last several weeks, maybe even into December, or it could be very short as it was in 2017, when we received a snowfall of nearly 11 inches at the end of October. But usually, early November is a time when we experience AutWin.

As I walk the woods, I see some green plants that stand out among the bare trees. Mosses, club mosses and ferns are easy to note and they are abundant. They have been present for months, but in the green foliage of summer, we were not likely to see them, as happens when they get covered by the impending snow. But now, I find these low-growing greens on the ground, logs and bases of trees.

Also on trees are the widespread and diverse lichens. Many will remain visible all winter, but not as much as in the present woods. A few trees, highbush cranberry, crab apples and mountain-ash, hold clusters of red berries. Here, I see a few birds and small mammals that have discovered these meals.

But there is more happening in the AutWin woods and some spiders and insects are also active.

The time of large spiderwebs is over, but spiders, especially small ones, are still present.

In the low angle of autumn sunlight, I see plenty of threads. These silk strands are not webs, but made by young spiders. They tell of their dispersal and travel.

In the breeze, spiderlings release threads that act as kites to carry them off to other sites. This movement is called ballooning or kiting. With trees now devoid of leaves, their travel threads are easy to see and quite common.

And I see a few insects as well. A white hairy-looking growth on an alder branch is a colony of wooly aphids. They remain active late in the season. In the waning sunlight, I note the movement of flying insects. I'm watching the mating flight of some autumn crane flies.

But when it comes to insects at this time, two moths tend to get our attention.

Frequently, on nights when temperatures are about freezing, moths appear at our windows. These drab brown-gray moths use this time to find mates and lay eggs; they do not feed. Cold weather may seem a strange time for their flights, but with fewer predators, they succeed. The other moth of note at this time is a caterpillar.

About 1-2 inches long with hairy growths covering the body, they are black on both ends with orange-brown in the middle. Though often seen in this caterpillar stage, most of us do not know the yellow adult.

Known as woolybear caterpillars, they are the larval form of Isabella tiger moths. It is common to see these woolybears now as they crawl over the roads. Why?

Unlike most others, these young moths do not winter in a cocoon, but as caterpillars. This is a crucial time for them as they move about to locate food and shelter to spend winter. Perhaps it is the black furry coat they wear or the fact that they are active before the coming cold that led to the myth of their forecasting weather.

They just want to find a good place to winter, and now we see them searching.

Retired teacher Larry Weber 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 c/o krohman@duluthnews.com.

Larry Weber

Retired teacher Larry Weber 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 c/o budgeteer@duluthbudgeteer.com.