Earthworm is an invasive species.
- Many earthworms eat the duff layer on the ground in the hardwood forest, reducing the available composting material on the forest floor.
- Don't dump worms in the woods.
- Dispose of unwanted bait in the trash.
How to identify earthworms
- There are thousands of species of earthworms across the world. The species found across the Great Lakes region originated from Europe and Asia.
- There are no native earthworms in Minnesota.
- Adult earthworms are easier to identify than immature earthworms. Adults have a collar-like structure (called a “clitellum”) near the front of their bodies.
- Earthworms are divided into three main groups by where they live within the soil: leaf litter dwellers, soil dwellers and deep burrowers.
- Leaf litter dwellers are reddish-brown, small and usually less than 3 inches long when mature.
- Soil dwellers live in the top 20 inches of soil.
- They are light gray and sometimes have a pink head and range in size from 1 to 5 inches.
- Deep burrowers dwell 6 feet deep but feed on fresh surface litter.
- Many earthworms are hermaphroditic but must have two worms cross-fertilize for reproduction.
- Some species can reproduce on their own from an unfertilized egg.
Aporrectodea, Octolasion spp.
- Angle worms eat the duff layer on the ground in the hardwood forest, reducing the available composting material on the forest floor.
- This change can limit native tree regeneration, improving soil habitat for some non-native species like buckthorn.
How to identify angle worms
- Soil dwelling, living in the top 15 to 20 inches of soil.
- Pink-peach toned with a well-defined raised band (clitellum) lower on the body than jumping worms.
- Lifespan varies from annual to a few years, depending on the depth of ground freeze during winter.
- Adults are killed by freezing.
- Eggs in cocoons deposited in the soil during summer and fall will survive and hatch in the spring.
- Jumping worms live in the leaf litter and the top few inches of soil on the forest floor.
- They do not burrow like other worms.
- They change the soil texture to appear like coffee grounds, strip the soil of nutrients and can kill plants.
How to identify jumping worms
Jumping worms are surface and shallow-soil dwellers.
They can be 1-1/2 to 8 inches or more in length.
They are similar in size to nightcrawlers or some of the larger angle worms, but their clitellum (collar-like structure) and coloring are different.
The clitellum is located 1/3 down the length of the worm from the head and it is smooth, cloudy-white and constricted.
As their name suggests, these worms may jump noticeably when disturbed.
Most jumping worms in Minnesota are likely annual.
- Nightcrawlers create and maintain a duff-free, mid-summer condition indefinitely in hardwood forests by eating the leaf litter from the previous season.
- This prevents a new duff layer from establishing.
How to identify nightcrawlers
- Nightcrawlers are deep burrowers but surface to forage for food.
- Adults can range from 5 to 8 inches long.
- Nightcrawlers have a swollen, collar-like structure (clitellum) that is saddle-shaped and does not go all the way around the worm’s body.
- Nightcrawlers have a slower life cycle and a longer lifespan than other worm species found in Minnesota.
- They generally hibernate below the frost line and lay relatively small numbers of cocoons.
- Red wigglers are used in composting.
- Although not currently thought to survive Minnesota winters, they could become a threat to native forests if they are found to survive and escape to native landscapes.
How to identify red wigglers
- Surface dwelling.
- 1 to 5 inches long with a strong red-brown colored backside.
- Fresh specimens have yellow bands in the grooves between segments.
- This species produces a pungent liquid when roughly handled.
- Worms hatch from cocoons and mature in about 30 days.
- Each worm has male and female organs, but they mate with each other.
- They can produce two cocoons per week and lay them near the soil surface.
Reviewed in 2019