About Worms: Earthworms are excellent soil builders.  They enrich poor soil by mixing it with their castings.  They aerate the soil by tunneling, encourage water retention, and provide microbes and nutrients that plants need.  The humus that is produced in vermicomposting improves the soil, stimulates plant growth, and helps control diseases that attack plants.* 

Red wigglers are the most commonly used composting worms for home worm bins.

* This information has been compiled from "The Worm Book" by Loren Nancarrow and Janet Hogan Taylor; published by Ten Speed Press; copyright 1998