Facts About Red Worms

One of more than 3,000 species of earthworms, the red worm (Eisenia fetida) is well-known for use in home worm farms to create mulch from kitchen waste in shallow containers. Red worms are also popular with fisherman to use as bait. Other common names for Eisenia fetida include "red wiggler," "striped worm," "manure worm" and "tiger worm." Both uses for red worms can lead to problems in local ecology.

Fun Fact

The species name for red worms used to be spelled "foetida" until 2004, when it was changed to "fetida."

Time Frame

Red worm eggs hatch at 32 to 73 days, depending on the temperature and humidity. The worms mature in eight to 10 weeks and can begin reproducing if they have enough food to support a larger population. Once sexually mature, a red word can lay two to three cocoons for six months of the year.

Geography

The red worm is native to Europe and Asia but can be found worldwide in temperate soils that match the temperature and humidity requirements for red worms. Uses in agriculture and fishing have spread red worms across multiple continents.

Features

Unlike common burrowing earthworms that eat small amounts of organic matter found in soil, red worms eat organic material such as leaf litter from the surface and within 10 inches of the surface. Worms such as Eisenia fetida that prefer living at the surface layer are called "epigeic."

These annelid (segmented) worms have from 80 to 120 segments. Red worms are identified by their alternating red and buff-colored stripes. More than one species of earthworm is called "red worm," and many are difficult to distinguish without a taxonomic key.

Red worms are small, varying in length from nearly 1 1/2 to just over 5 inches (35-130mm), but normally reaching an adult length greater than 2 3/4 inches (70mm). In diameter, mature red worms range from 3 to 5mm.

Considerations

Experts at the Whatcom County Extension Office at Washington State University note that 1 lb. of red worms will consume 1/2 lb. of food per day. But for anyone wanting to raise red worms as composters in shallow bins, it's important to be aware of what they will not eat. To get the best castings and happiest red worms, avoid acidic food waste, meat or dairy. Feed the worms fruits, vegetables, egg shells, cereals and coffee grounds. Maintain an even temperature between 55 and 77 degrees Fahrenheit (12 to 25 C). Red worms can tolerate temperatures as high as 90 F (32 C) but prefer 70 to 75 F (21 to 23.8 C).

Warning

Some people warn that importing earthworms not native to a particular area endangers the local ecology should those earthworms get loose and begin burrowing. This theory is not well-studied and is subject to debate. Ecologists believe earthworms native to northern regions of North America died out during the last ice age, and that species of epigeic earthworm that have naturalized in North America since then, such as the red worm, pose little threat in most areas. Clive A. Edwards, PhD, an earthworm ecologist from Ohio State University, has published information on the effects of exotic earthworms in North America and other regions. Red worms are unlikely to survive freezing temperatures in Minnesota, the region most concerned with damage from non-native earthworm species; however, people are cautioned not to dump worms, from bait or composting, in the woods. Consult your local extension office to learn the appropriate way to dispose of used worm compost bedding, to avoid spreading possible invasive species. Since red worms eat leaf litter, and some forest ecosystems depend on leaf litter for seed growth, red worms can become a problem in these regions.

References

• Redworm (Eisenia fetida)
• Composting with Redworms; Whatcom County Extension Office, Washington State University
• Wormpost Northeast

Resources

• Ecological Risk Assessment of Non-indigenous Earthworm Species; Minn. Dept. of Nat. Resources 2003
• Worm Species and Categories
• Invasive Earthworms