Lifecycle of earthworms

The life-cycle of the compost worm Eisenia fetida (Oligochaeta) was evaluated in a sicentific study by Venter and Reinecke im 1988, published in the South African Journal of Zoology, Volume 23, pages 161 to 165.

Eisenia fetida were placed in a cattle manure medium at optimal temperature and moisture levels and observed for 600 days. Earthworms were shown to:

• be reproductively active for more than 500 days
• Each cocoon produced 2.7 hatchlings on average, after an average 23 days of incubation.
• Hatchlings attained sexual maturity after 40 to 60 days
• In another study by Spurgeon and Hopkin in 1996 showed earthworms produce one to 2 cocoons per week on average. Only some of the cocoons are fertilized and some of the hatchlings survive

In a study by Tripathi and Bhardwaj in 1994 Eisenia foetida was shown to produce 9 net hatchlings per months.

Information from scientific publications on earthworms is accessible from scholar.google.com (or at least the abstract is).