Dendrobaena hortensis

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Dendrobaena hortensis, the European nightcrawler, is a small to medium earthworm. An adult weighs about 1.5 g. It is usually blueish or pink-grey with a banded look, and the tail tips are cream or pale yellow. When it hasn’t eaten, it can be pale pink.

Habitat and range:
It lives in deep woodland litter and garden soils that are rich in organic matter, mainly in Europe.

Uses and name notes:
It’s sold mainly as fishing bait, but it’s also popular for composting. It was once placed in Eisenia, and is part of a species complex with Dendrobaena veneta. In vermicomposting, the two are often treated similarly. The name D. hortensis is more common in North America, while D. veneta is more common in Europe.

Reproduction:
D. hortensis is hermaphroditic, meaning each worm has both male and female organs. During mating, one worm often takes the female role, which costs more biologically. Two worms join at their clitella (the lighter bands around the body) to exchange sperm. They may produce lemon-shaped cocoons that are pale yellow at first and turn brown as embryos mature; cocoons are visible to the naked eye.

Life stages and buying:
Worms can be bought as cocoons, juveniles, or adult breeders. Cocoons hatch into juveniles, which grow into adults that reproduce. Adults are common when buyers want quick setup; cocoons are useful for starting a new population.

Care and suitability:
D. hortensis does best in environments with a higher carbon-to-nitrogen ratio (more browns), making it good for fibrous compost materials. They can be invasive in some places, so they should be used only in contained compost systems in parts of the world with northern deciduous or boreal forests.