Common Earthworm

Common Earthworm

(Lumbricus terrestris)


During the previous ice age, when Canada was almost entirely covered in a thick layer of ice all of our native earthworms died. After this glacial period, our forests regrew and evolved without earthworms. Today earthworms are very common in most forests as they have been introduced through various methods such as anglers dumping bait or gardeners releasing them. Contrary to popular belief earthworms are actually bad for our native forests, the earthworms decompose leaf litter at a rate that is unsustainable for our ecosystems, leaving bare soils exposed.


Earthworms are found as far north as the territories however their distribution correlates to areas inhabited by humans. Throughout Canada the populations of earthworms are similar, being mostly where humans have developed.

Impacts & Control

They alter our natural forest processes, which can negatively affect things like water quality and seedlings. This also changes the composition of our soils affecting nutrient balances. This severely affects historic old-growth cycles. To control the spread, be aware when transporting soil, repotting plants and dumping fishing bait. Oftentimes people dump old plants in the woods, but this can spread earthworms to new areas. 

-The changing of soils chemistry and ecosystem balance affects American ginseng populations, this species of ginseng is extremely sensitive to changes in its ecosystem.

A fasciatus on species of invasive slug

Feature Invasive Slugs

(Arion rufus, A. fasciatus, A. fuscus)

There is a variety of invasive slugs which also affect American ginseng as they have been found to dine on the young growth in the spring. There are not large quantities of populations currently established but there is potential for future expansion and that will be a severe threat to the already struggling American ginseng.

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