Earthworms are hermaphrodites. The term "hermaphrodite" derives from the combination of the names of two Greek gods: Hermes, a male and Aphrodite, a female. Thus, a hermaphrodite is something with both male and female characteristics. With worms, each individual contains both male and female reproductive organs. However, each worm must still mate with another worm of its species in order to reproduce. When two worms mate, they lie alongside one another, and both transfer sperm to the other. Each will lay one or more cocoons which contain the worm eggs.

Once these eggs develop, fully-formed, but very tiny worms will emerge. The familiar thickened "band" near the front end of most worm species is a structure called the clitellum. It secretes the mucous and other substances that form the capsule containing the fertilized eggs. In nature, earthworms normally mate and lay eggs primarily during the spring and fall, when soil moisture levels tend to be higher. However, since most Southern Californian's water their lawns and gardens throughout the spring, summer and fall, and since our winters tend to be very mild, the earthworms around your house will likely reproduce throughout the year. Earthworms usually mate and lay eggs several times each year, but produce relatively few offspring per year, perhaps only 10-15 for each adult worm. It may take the tiny worms up to a year to reach full size and sexual maturity.

How long an earthworm can live in the wild isn't certain, but researchers estimate a normal lifespan of about 3 years. Captive earthworms (in a worm composting bin) have been reported to live as long as 10 years!  Earthworms can eat many kinds of organic matter, including dead plant materials (dead leaves and other plant debris), soil micro-organisms (protozoa, nematodes, bacteria, fungi, etc.), and the remains of larger dead animals. They feed by swallowing organic matter or bits of soil containing organic matter. This passes through their gut and is finally deposited as castings (simply put - worm poop) which the worms pass out when they are at the surface. Presumably this helps them to keep their tunnels clean and open. Earthworms also act as food for a wide variety of soil predators. Just about anything that likes a bit of animal protein will eat worms: insects, fish, frogs, toads, snakes, mice, moles, gophers, raccoons, opossums, as well as most kinds of birds. For animals that weren't originally found in Southern California, worms now occupy a very important slot in the food web.