There are over 4400 species of earthworms identified, and more are being discovered each year. The terrestrial worm species are divided into three subdivisions based on their relationships and activities in the soil.

Anecic worms build permanent, deep, vertical burrows in mineral soil, and feed on organic matter. These worms live longer and have low reproduction rates. For example, the common night-crawler (Lumbricus terrestus), moves up or down in the soil as temperatures fluctuate with the seasons.

Endogeic worms build extensive, semi-permanent burrows in the upper layer of mineral soil, feeding on minerals and organic matter. They have moderate reproductive rates and life span. Endogeic worms are also very soil temperature specific. They have low pigmentation and are smaller worms than night-crawlers. These worms are often found crossing or left stranded on pavement during and after rain. But why? For several reasons: the worms are migrating, avoiding competition with their young and seeking mates. They move above ground more efficiently and safely when it’s wet and overcast, shading them from the drying rays of the sun. Because pavement is a relatively new obstacle to the worms, they become stranded before they reach soil they can burrow in.

Anecic and endogeic worms have been calculated to mix and turn soil at a rate of up to ten tons a year per acre.

Epigeic worm species are commonly used as composting worms. Composting worms have no permanent burrows and live in loose, shallow, organic-rich soils (under mulch and leaf litter). They tolerate a pH from 2-9, medium to high moisture levels and temperatures from near freezing to above 90 degrees. However, Eisenia fetida, the worms primarily used in vermicomposting, can double their population every few months in 50 to 75 degree conditions. These worms will easily eat and digest at least half their own weight of decaying organic matter in 24 hours. In general, if it grew from the ground, worms can turn it back into the soil.

Knowing the moisture level, temperature and what they eat are the most important things needed to practice the art of small-scale vermicomposting. Worm beds can be as simple as a wet pile of leaves and vegetable matter with a piece of carpet over it, to fancy continuous flow reactors with moving parts and elegant designs. Beds in contact with the ground are the easiest and most forgiving to manage.

According to Sam James, a prominent taxonomist, there is no indigenous species of worm in areas of the desert west of the United States. European settlers brought worms to Colorado in the soil of their transplants and the gut and hoofs of their animals.

The Chinese have used worms with great success for at least 2000 years for pharmaceutical preparations. Worms have only recently been utilized in Western science for ecototoxicoloy, cancer research, studies on the nervous system, immunology and human fertility.

Sophie Reinecke, a prominent high-tech researcher from South Africa, spoke of the lowly earthworm, “It just might be that these ‘simple’ creatures could play an even more important role in the survival of life on this earth than we have ever dreamt of.”

For more information on vermicomposting, visit: www.bae.ncsu.edu/topic/vermicomposting/vermiculture

The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.

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This page updated:  May 9, 2007