“Out There” is a column by Ed McMackin, a biologist by training and a naturalist by nature. He may be reached at 250-866-5747
About this time of the year, some people would just like to sleep off this winter wrapped up in a warm blanket, escaping the cold and the virus kerfuffle. But most people would not want to do that, or, could do that. Only bears and a few other creatures are equipped to hibernate. Squirrels and some other mammals will go through the winter in a state of dormancy, waking up on warm and/or sunny days, until spring arrives.
Many creatures in the Kootenay Lake region that go into some kind of dormancy for the winter, or just seek protection from predators or inclement weather, seek shelter in protected places, such as burrows, under bank overhangs, in cavities under rocks and tree roots, in brush piles, tree cavities, under bark and in old nests.
A few creatures go through a winter prep routine, such as building a nest, stowing winter food, or, actually constructing a “body wrap” or “bag.” Beavers and rock-rabbits put away food for the winter. Some birds, like Jays and Clark’s Nutcracker, stow food in bark crannies or tree cavities.
Probably, one of the most intricate works done for winter is completed by some species of moths that spend the winter in the pupa stage — the stage between larva and adult — enclosed in a protective covering.
Perhaps, the most notable of these moths are what are called the “silk moths.” They construct a “cocoon” about themselves, woven from a number of strands of silk produced in their body. Glued together with their own adhesive making, when dried, it’s a very tough winter protection, which is difficult for even birds to peck through.
The cocoons are usually dark or light brown and may, as with the Polyphemus Moth (Antheraea polyphemus), include a dried leaf or two. The more elongated cocoon of Glover’s Silk Moth (Hyalophora gloveri), has silver coloured streaks, while the Polyphemus cocoon is oval in shape.
The cocoons, five to six cm in length, of the large silk moths are relatively easier to find than the cocoons of other smaller moths. Not all cocoons are constructed in the fall, but, like some of the tiger moths, in late spring, after the caterpillar has hibernated as a larva and done some feeding.
The woolly bear caterpillars, with black and red bands of stiff “hairs” — immature of the Isabella Tiger Moth — may be found, during winter and early spring, curled up under rocks, boards and in leaves or wood chips. Sometimes they are covered in frost. In late spring and early summer, they may be found crawling about looking for a site to make their cocoon of stiff hair.
Some moth and butterfly species, which spend the winter in the larva-caterpillar stage, roll up in a leaf for the winter. During winter, one may find many curled up leaves on shrubs. Most of them probably don’t conceal a caterpillar. It’s a tedious task to examine every leaf.
The Lorquin’s Admiral (butterfly) leaf-encased caterpillar may be found, in winter, hanging from a cherry, willow or poplar twig. Now, back to the silk moths.
The Chinese Silk Moth, a relative of our local species, used to be reared for the silk that could be obtained from the cocoons. The cocoon was woven of one thread, making possible the unwind from a treated cocoon. It is this silk, woven into silk materials, that I believe was imported from Silk Moth farms in China and carried by specially guarded trains, from the west coast of Canada and the United States to the eastern cities.
Queen Elizabeth’s coronation velvet robe was made of silk from the Chinese Silk Moth (Bombyx mori). Attempts made to use the silk of native North American Silk Moth cocoons were unsuccessful, as the cocoon is woven of two many individual strands. Let’s find out where to look for cocoons in the Kootenay Lake Region.
Cocoons of the Polyphemus Moth may be found hanging in young trees of maple and birch, but they may also be found at the base of a tree in some of the protective grass, or a few feet away, attached to a woody twig of some other small shrub. (I once read in a report of a study done, which stated that, when the winter was unusually cold, the cocoons were made close to the ground and, if mild, were made high in the food plant).
The best shrubs to check out are those that are somewhat isolated or standing alone, along a rural road, hedgerow or field border. Cocoons of Glover’s Silk Moth may be found on or near the food plants – cherry, willow, alder, wild currant and a few others. The few that I have found were under 0.5 metres from the ground.
Not all cocoons one finds will be “occupied,” as the moth may have already emerged or the larva may have been parasitized, evidenced by small holes in the cocoon and its lightweight. A “hatched” Polyphemus cocoon will likely be open on the top end.
Cocoon hunting is not likely everyone’s “cup of tea.” However, for those who dare to “act out of the box,” add a bit of diversity to their walks, which we seem to be doing more of due to the virus. You may find cocoon hunting another dimension to add “spice” to the outing. Just one reminder, though, if you find a cocoon and take it home be sure you replicate the same conditions for it as would exist in its original location.