Worms used in composting consume vegetable scraps, rinds and peels at one end and deliver nutrient-rich castings at the other end. As with other worms, composting worms have a different sex at either end; they live in masses and work on the surface. In addition to adding the nutrients of their castings, worms aid decomposition in a composting bin by keeping the mixture loose and aerated.
The worm most often used for composting and widely available commercially is Eisenia fetida (E. fetida), also called the red wiggler, red worm, branding worm, and manure worm. E. fetida are about 1 1/2 to 2 1/2 inches long. A red wiggler will live from two to five years; during this time it will produce from two to five cocoons each week. Each of those cocoons will hatch two or three worms in about six weeks.
Two pounds of E. fetida will consume about one pound of organic scraps each day, and will work well in a bin that is two feet deep and three feet wide. E. fetida must be kept in heavily-insulated bins during freezing winter weather. During this time they go dormant and cease breeding and composting activity.
L. rubellus are popularly called the Garden worm, Angle worm, Leaf worm, Drift worm, or Red March worm. L. rubellus grow up to four inches long as an adult. They will survive for weeks in the refrigerator.
Although both E. fetida and L. rubellus live on the surface, L. rebullus can tunnel more deeply into compost in order to survive freezing winter weather. It can tolerate temperatures of 38 to 40 degrees Fahrenheit, so gardeners with composting bins in cold weather prefer it to E. fetida.
Eisenia Andrei, a close relative of E. fetida, is also called the red tiger worm or tiger worm. E. Andrei is deep red or purple with a yellow band that separates the two sexes.
Eisenia hortensis is popularly called the European night crawler. It is a slow breeder, sometimes needing a year and a half under good circumstances to establish a maximum population in a composting bin. E. horensis likes a moist environment and cool temperatures.
Perionyx excavates, also called the blue worm, is a small, aggressive breeder. Many who have it in their composting bins think it is a nuisance. It can crowd E. fetida, a superior composting worm, out of a bin. It likes warm temperatures and is a native of the American South.
Lumbricus terristris, also known as the Canadian night crawler, is a large worm that can be used for composting, but is generally not recommended. It is often grown for fishing bait.