Worms, Pacific Northwest
The Dew Worm is found in great numbers all along the coast of the Pacific Northwest. They are a common species of earthworm that is active at night but will also come to the surface during wet or rainy weather and crawl about. They will often leave casts on the surface which make lawns bumpy and uneven. Dew worms are more common on older, shaded or heavily watered lawns.
Dew worms are extremely valuable in creating topsoil and maintaining soil fertility. Earthworm castings, or excrement, are richer in minerals than the soil which the earthworm has swallowed. The earthworm constructs its burrow by forcing its front end through crevices and swallowing soil. The eaten soil and mucus mixture is removed from the burrow as castings. During dry seasons or during the winter, earthworms migrate to deeper levels of the soil.
Earthworms are scavengers and feed on the dead organic matter at the surface of the soil and may pull leaves into their burrows. They will also feed on organic matter obtained from the soil that is swallowed during their burrowing.
They are most common in moist soil rich in organic matter, or with at least a layer of hummus or thatch on the surface. Young worms and small species are usually found in the top few inches of the soil, while others will have a wider distribution but are still limited to the upper level of the soil that contains some organic matter. The tunnels of larger species range from the surface to several meters in depth, depending on the soil.
It seems strange to think of earthworms as immigrants. After all, they seem to be everywhere, performing their lowly task of working the soil. It seems impossible that they could not always have been here and yet, in many parts of North America there were no worms until they were transported here from Europe and elsewhere by yet another invasive species, the humans.
At least since the end of the last ice age, for the most part, North America has been an earthworm-free zone.
In North America, the ice age glaciers scraped away the topsoil along with most of the worms it contained. When the glaciers retreated about 10,000 years ago, the northern forests grew back without the help of worms.
Then came the Europeans, bringing with them plants, as well as the dirt those plants were growing in and the worms that dirt contained. Worms were also introduced intentionally, as a way to fertilize and improve the productivity of European style vegetable gardens, they were transported in the ballast of sailing ships too.
On Dec 24, 2012, l was walking through our woods, trying to get a photo or two of a red-tailed hawk. As I was slowly walking through the snow, trying to make as little noise as possible, keeping my eye on the hawk, l happened to glance down and to my amazement, the snow was covered by yellowish-white worms, there must have been hundreds of them. They were about 3 maybe 4 cm long and quite active. In all my years hiking the forests of Vancouver Island, l had never seen these little guys before. I was absolutely fascinated, to say the least. I was surprised at just how active they were in the sub-zero weather. Snow Worms.
The Snow Worm look quite a bit like Ice worms, except that ice worms are never found away from glaciers and are usually a much darker color, some that l have seen were almost black. These worms were at least thirty km from the nearest glacier.
So I forgot about the hawk and took some photos and a video of them. Then headed home and started to do some research on them. Apparently, they are not normally very common, but for the last couple of years, they have been showing up in quite a few places on the Island. They are also showing up in Washington state and in a few places back east.
They are not a new thing though, They made big news back in 1884 in New York State, after a heavy snowfall, there were yellowish worms seen crawling out of the snow, this was happening in quite a few places and the worms were scaring the people big time. The story states that the worms seem to have fallen from the sky and were an evil or bad omen, some were saying that it was a foreboding of a cholera outbreak and others were saying that the worms would crawl onto humans and attack them by crawling into their rectums. There were stories that the worms would attack young ladies by crawling inside the uterus and eat the eggs stored there, making the ladies infertile. Apparently, the worms did not like hair and very seldom attacked men, women started letting their leg hair grow. It’s amazing how people could be scared back then.
Loggers from the forest said they saw these Snow Worms and the deer eat them right up as if they were really enjoying them. So you see they have been around before.
Recently, they were observed in Washington state and samples were sent to the Burke University and they were determined to be earthworms. Juvenile earthworms.
I will be looking into these worms and will post all l can find out about them here. If you know more about them, please write to me so l can inform my readers about them.
When this worm gets dug up or otherwise disturbed, it will flip-flop around, sometimes gaining several cms of distance from the ground, quite fascinating to see.
I have seen this worm a few times in my youth when l was a firefighter for the forest service, it would be living in the duff and it appears to be quite tolerant of heat.
It has only been observed in parts of Washington State and on Vancouver Island. It has been seen in several areas of the west coast of the island and in a few spots around the Cowichan Lake area. There are quite a few in the Campbell River area.
During the last ice age, most North American worms had not survived with the exception of a few. The forests began to rely on nutrients that would slowly be released from the leaf mulch that would build up at their base. Over thousands of years, the trees evolved to survive this way. But when the Europeans began arriving in their big sailing ships they inadvertently brought the worms with them. They would use dirt as a ballast in the holds of the ships which would be discarded here to make room for goods that would be loaded for the journey back to Europe. The soil was loaded with worms. They also brought potted plants by the thousands that had worms in the soil.
Earthworms are extremely efficient in both aeration and fertilization of soils, farmers from Europe were very familiar with this and help spread the worms very quickly. The worms can move the leaf mulch down into the soil in a relatively short time span and after eating it, they cast their droppings on the surface. Charles Darwin once estimated that earthworms could move up to 100 tons of soil per hectare, per year. Just think about that, it’s pretty amazing.
Anyone in North America who turns over a rich shovel full of garden dirt is likely to find that dirt literally crawling with at least one non-native earthworm species. For instance, the dew worm that is so prized by fisherman are native to Europe, not North America, and so are the several species of red wigglers that are so common to our gardens and compost bins and in terms of sheer numbers, the migrants thoroughly overwhelm the natives in most places.
Despite their green card status, however, most people view earthworms as beneficial, especially when they are tilling and fertilizing a garden or rendering compost into black gold.
But in ecosystems that developed without worms can actually cause harm. for instance, the ecology of northern forests often depends on a thick layer of leaf litter remaining on the ground throughout the year. But earthworms remove that leaf litter by converting it to topsoil and that seemingly benign action has so completely changed the chemistry and biology of the forest that some native plants and trees are no longer able to grow there.