We get asked this question over and over.
Believe it or not, all worms are not created equal. There are three main types of worms, each one has different characteristics that make them unique.
Each one of the 4400 + named species of worms on earth can be broken down into these three main categories:
Anecic (Greek for “out of the earth”) – these are burrowing worms that come to the surface at night to drag food down into their permanent burrows deep within the mineral layers of the soil. The common nightcrawler (also known as Canadian Nightcrawler, Dew Worm & Common Earthworm) is in this category. These worms build vertical permanent burrows that extend over six feet below the earth’s surface. Believe it or not, but these worms can actually recognize their own burrows and return to it day after day.
These worms feed on decaying litter and therefore must visit the surface on a regular basis. They are solitary worms and do not like living in high worm populations.
Endogeic (Greek for “within the earth”) – these are also burrowing worms but their burrows are typically more shallow and they feed on the organic matter already in the soil. These worms are the only type of worm that will actually eat soil as well as decaying organic material. These worms rarely come to the earth’s surface and spend most of their time underground in their lateral burrow systems.
Epigeic (Greek for “upon the earth”) – these worms live in the surface litter and feed on decaying organic matter. They do not have permanent burrows. These “decomposers” are the type of worm used in vermicomposting. These are our special little garbage men that work for food. They thrive in large groups and are surface feeders, not burrowers. Red Wigglers & European Nightcrawlers are both categorized in this group of composting worms. Becuase they do not build burrows, they do well in worm bins and appreciate the constant food source and moist environments that we provide for them.
I hope this helps you to gain a little understanding of the workings of earthworms and why purchasing the right kind of worm for your bin is important to your success.