Worm Anatomy 101: The Reproductive System
All worms have both male reproductive organs and female reproductive organs. This means that they are hermaphrodites. The female organs of a worm include the egg sacs and ovaries. The male organs are two pairs of testes, three pairs of seminal vesicles and sperm funnels. Despite the fact that worms have both male and female organs; it must mate with another worm in order to reproduce its own kind.
Worms will never reproduce beyond the carrying capacity of their habitat. This means that worms living in vermicomposting bins won't over crowd the bin. So you never have to worry about having a surplus of worms to deal with.
After fertilization, the clitellum secrets a kind of tube that forms the cocoon in which several eggs will be fertilized, and eventually turn into live baby worms. Each cocoon can have 2-15 babies. One worm can make up to 3 cocoons in a week. The cocoons will hatch in 4-6 weeks. A worm is sexually mature in 6-8 weeks.