There are a few species of worms used for composting. By far the best worm to use is the Red Wiggler worm or Eisenia fetida. They will consume organic matter quickly, half their body weight every day. So, if you start with 1 pound of red wigglers, each day they are consuming 1/2 pound of food.
They multiply quickly increasing your vermi-composting capacity. With conditions remaining good, red wigglers will double in population within 60-90 days!
These worms will not "move out" as long as there is plenty of food and moisture. Small spaces do not bother them making them excellent to live and thrive in home worm bins.