28 March 2010 ~ 14 Comments

All About: Cocoons, Hatchlings, Juveniles and Adult Red Worms


A cocoon is a small, yellow, lemon colored and lemon shaped object that is produced by red wiggler mating.  It is about the size if the letter ‘O’. According to C. A. Edwards and P.J. Bohlen in Biology and Ecology of Earthworms: Eisenia Fetida can produce as many as 198 cocoons per year. Gestation occurs over a period of eleven weeks.  The cocoon is hardened mucus and, like a bird egg, contains all the necessary nutrients for the development of the hatchlings. On average three will emerge.

Climate conditions directly effect cocoon production, for example, when there is too little moisture in the bin, the worms will cease reproduction.  Peak production occurs when ambient ground  and air temperatures are between about 65-80F’  or 18 to 27C’ and the environmental moisture content within 80 to 90%.  That means moist to the touch, but not dripping ( like a wrung out sponge).

When environmental conditions are not appropriate for survival, the cocoons have been known to survive for up to three years under extremely dry conditions, without being adversely affected.


It take five to eleven weeks for the cocoon to mature and hatch.  The newly hatched worms first appear as tiny white, thread-like creatures.  In approximately eight hours they gain their hemoglobin and change color from white to pale pink to brick red.

Depending on the bin conditions, temperature and moisture, hatchlings can take from 53 to 75 days to become sexually mature, that’s about two and to tow and a half months. The complete generational cycle from one adult worm to the next is anywhere from three to five months.


Adolescence is a short lived phase for red wigglers.  The length of the worm increases almost daily as their principal function during this phase is to eat, eat, eat!

Like many creatures sexual maturity in Eisenia Fetida is delayed by cold weather, but not growth rate.  Lobsters raised in cold water compared to warm water are a good example.  Those raised in cold water grow fairly large before they become sexually mature, while warm water lobsters are smaller upon reaching maturity.

Juvenile worms are distinguishable from adult worms because they look the same from head to tail and do not have the band indicating the clitellium.  They are the same color as the adults and may be just as large.

Red wigglers spend an average of 56 to 72 days or about 8 to 11 week in this developmental stage.


Adult red wigglers are characterized by the formation of their bulbous clitellum. The presence of the clitellum means they are sexually mature.

Diet plays a key role in the worm’s size, which may vary from 4 to 7 inches.  Smaller size does not mean that something is wrong, but small worms produce smaller cocoons and fewer offspring.

There is no conclusive evidence that gives a definitive life expectancy for worms.  However, a well cared for worm population in your bin may give you sterling service for up to five years or more.

To Recap:

> Hatchlings are delicate. Their outer casing is fragile. I always wear gloves while working in the bins here, as the sweat glands on our hands can destroy the future generations of worms, if they come into contact with  the sweat.

>  Juveniles: are always hungry. Just like teenagers!

> Adults will do much better in your bin if they are kept at the most even temperature you can, add adequate bedding as needed and give them a varied diet.

Until next time when I will write about keeping worms, I hope you learn from your worms and enjoy your bin.