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Earthworms

Quick facts

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.

Earthworms are not regulated in Minnesota. They are monitored on Great Lakes Worm Watch.

How to identify earthworms

  • There are thousands of species of earthworm 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 body.
  • 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.

Life cycle

  • Many earthworms are hermaphroditic but must have two worms cross-fertilize for reproduction.
  • However some species can reproduce on their own from an unfertilized egg.

Angle worms

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 well-defined raised band (clitellum) lower on the body than jumping worms.

Life cycle 

  • Lifespan varies from annual to a few years, depending on 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

Amynthas spp.

  • 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 night crawlers 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.

Life cycle 

Most jumping worms in Minnesota are likely annual.
 

    Night crawler

    Lumbricus terrestris

    • Night crawlers 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 night crawlers

    • Night crawlers are deep burrowers but surface to forage for food.
    • Adults can range from 5 to 8 inches long.
    • Night crawlers have a swollen, collar-like structure (clitellum) that is saddle shaped and does not go all the way around the worm’s body.

    Life cycle

    • Night crawlers have a slower life cycle and longer lifespan than other worm species found in Minnesota.
    • They generally hibernate below the frost line and lay relatively small numbers of cocoons.

    Red wiggler

    Eisenia fetida

    • 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 strongly red-brown pigmented back side. 
    • Fresh specimens have yellow bands in the grooves between segments. 
    • This species produces a pungent liquid when roughly handled. 

    Life cycle

    • 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. 

    Angela Gupta, Extension educator; Amy Rager, Extension educator; Megan M. Weber, Extension educator

    Reviewed in 2019

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