They grow to be 3-8 inches long, and are 2 or 3 times bigger than their smaller cousins, the red wigglers (Eisenia Fotida). The euros are certainly better for larger foods that aren't as broken down, or for leaves and other tougher material that has not been pre-composted. Can be successfully introduced to most garden environments. They are mid range dwellers and will till and aerate your soil for you, while supplying valuable castings. This pack contains approximately 600 worms to a pound.