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The goldenrod gall fly survives winter

The insides of a goldenrod ball gall. Note the curled larva of the goldenrod gall fly. Also note the excavated route that the larva made to use when emerging in spring. (Photo by Larry Weber)1 / 2
A goldenrod ball gall as seen in the winter. (Photo by Larry Weber)2 / 2

January may be a bit chilly and snowy, or it may be a time when we experience a thaw. But regardless of the weather, I find these midwinter days an excellent time for walks. The freezing rain that fell on Christmas now seems like only a distant memory, but the snowpack in the woods still holds that ice coat. Even though plenty of new snow has fallen to cover this December phenomenon, it is still present and I find that any steps off the trail in the woods or yard is hard walking. Each step is dealing with the crusty crunch of the ice-covered snow that formed at that time. And so, my walking has been on packed trails or along the roads. However, these excursions into the Northland winters are always valuable treks that reveal much happening in the world of nature.

Regardless of the conditions, there are always new track messages in the snow. This will vary with temperatures, but I regularly see the routes of deer, coyotes, foxes, squirrels, mice, shrews, hare and rabbits as they move about. Occasionally their marks are joined by tracks of some members of the weasel family: weasels, martens or fishers. And there are the ruffed grouse out seeking food and shelter. Recently, right on the trail in front of me, I found where a grouse had buried itself in the snow to wait out the weather conditions. The snow imprints told of where it entered. Droppings showed where it stayed. And wing marks on the snow's surface recorded its exit.

Besides all these signs of moving wildlife, they are usually without the sight of the critters themselves. I see and hear others that are present. It is a rare morning walk that does not have the sights and sounds from ravens overhead. These hardy birds seem to survive anything. Their cousins, the crows, are often present and a barred owl calling at dawn is a great addition, too. Even with this going on with the local animals, more is seen along the walks as well. The roadside and fields are great places to see the abundance of the wildflowers from last fall.

These plants gave us plenty of colorful blossoms as they grew and flowered at that time. Starting in summer, July or August, they thrived throughout these days and into the autumn. They got the attention of insects, were pollinated and formed seeds. Eventually, in the frosts and lessening daylight hours, they succumbed and passed on. We no longer saw the yellows, whites and purples that showed here for weeks. They appeared to be dead.

However, these hardy plants, most of which are perennials, still survive. They may look like dead sticks along the roads, but they have two crucial parts that are alive. Underground, the roots survive the cold while above, their seeds are able to cope with the seasons.

Even without colorful flowers or green parts, we can still recognize lot of these plants. As I walk by I see goldenrods, asters, yarrows, tansies, thistles, sunflowers, milkweeds and primroses. Many take advantage of the breezes and are scattering their seeds on these winter days. Others rely on their seeds to be eaten by animals; mostly birds, for dispersal. I expect to see these kinds again next year. But there is more here.

On many of the goldenrod plants, I see swellings that tell of another critter present. These thick growths are known as galls. They show the activity of insects on these plants. Many plants have galls on them and in summer, it is easy to find galls on oaks, cherries and blackberries. Generally this growth is caused by a reaction of the plant to insect eggs. An insect places an egg here and the plant swells up. The insect grows up and leaves. Most of the galls seen on a winter day are empty, but not all.

On this subzero day, I find a goldenrod gall that is still lived in. On the stem of the goldenrod is a ball-shaped swelling. Composed of the plant cells of the stem, it is hard. And inside is the larva of a fly. The insect that did this is so attached to goldenrods that it is known as a goldenrod gall fly. Even the scientific name has solidago, the genus for goldenrod, as part of its label.

The egg was placed here last summer. It hatched to become a worm-like larva called a grub. It survives these cold days by ridding itself of moisture (no ice) and forming a type of antifreeze in its body. Before going dormant, it excavated a route towards the outside. Upon awakening in the spring, the larva will form a pupa and then as an adult fly, it leaves on its constructed route. The tiny fly will mate and lay eggs in the new growth in summer.

It may be January, summer is far away, but here on this chilly day, I find a critter that is preparing for its life in the coming warm months. And if it is not discovered by chickadees or woodpeckers, it will survive.

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.

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