Red Wiggler Reproduction and Life Cycle Explained
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Time to read 7 min
Table of contents
Red Wiggler Cocoons Watch a Red Wiggler Lay a Cocoon Red Wiggler Cocoon Identification and Size How Long Does it Take for Red Wiggler Cocoons to Hatch? How many Red Wigglers can be in a cocoon? Cocoon Misidentifications Red Wiggler Hatching & Baby Worms Red Wiggler Hatching from a Cocoon Common Mistake: Baby Red Wigglers vs. Potworms Earthworm Growth Adult Red Wigglers Reproduction How Fast Do Red Wigglers Reproduce? Theoretical Worm Reproduction Charts Do Red Wigglers Reproduce less as they age? Buy Red Wigglers
Red Wiggler Cocoons
When deciding how to start this post I had to ask myself.. which comes first? The earthworm or the cocoon?
Unsure of the answer, I decided to start the post the same way that earthworms begin theirs. In a cocoon!
An earthworm cocoon itself is not an egg, but more similar to a capsule to protect fertilized worm eggs inside of it. Baby earthworms spend as little as 14 days in these cocoons before hatching, but can also spend several months, and possibly years, while waiting for ideal conditions to hatch.
On average, around 3 baby worms will come out of each cocoon, but as many as 7 babies can come from a single cocoon.
Cocoons, when laid, are white and almost transparent, but quickly darken to a yellow color. When the worms are about ready to hatch it will get even darker, appearing like a dark yellow-brown. Just before they hatch, you will be able to see the baby worms wiggling around inside of them.
This video, played at 2x speed, shows a cocoon being laid by its mama red wiggler.
Watch a Red Wiggler Lay a Cocoon
Red Wiggler Cocoon Identification and Size
Cocoons are typically around 1/8th inch diameter, but their size can vary a bit. For most of the worms incubation time, the cocoon will appear yellow and slightly translucent, but will become darker with time.
The cocoons are mostly spherical besides a tapered end - where the baby earthworm will eventually exit the cocoon.
Here's a bunch of pictures of cocoons at different stages of maturity displaying their different colors, and size.
How Long Does it Take for Eisenia Fetida Cocoons to Hatch?
A cocoon can hatch in as little as 14 days, but closer to 23 days is much more typical.
The red wigglers in the cocoons have some say on when they hatch.
Generally, the closer to 77°F or 25°C the quicker they'll decide to hatch. Cocoons can wait through winter until spring to hatch if outdoors.
Anecdotally, people report that placing fresh food near cocoons will help them hatch faster too.
(Venter and Reinecke 1988)
How many Red Wigglers can be in a cocoon?
Scientists have found that the strongest correlation for how many baby earthworms are in each cocoon is temperature. Generally, the cooler the temperatures are, the more hatchlings. This chart shows the average red wiggler hatchlings per cocoon at 77°F or 25°C.
(Venter and Reinecke 1988)
Cocoon Misidentifications
Fertilizer pellets, like the ones you see in potting mixes, and snail eggs are often mistaken for red wiggler cocoons.
The easiest "tells" are that fertilizer pellets are perfectly spherical, and snail eggs are typically in "clutches" of many eggs. Red wigglers just lay one cocoon at a time, so they will be more scattered than snail eggs.
Baby Red Wiggler Worms
Red Wiggler Hatching from a Cocoon
After as little as 14 days, the red wigglers inside will exit the cocoon through the tapered end, visible in this instagram reel. On "birth" the baby worms are extremely small and nearly see through with a slight pink hue. It can be very difficult to see them unless they are against a contrasting background (like dark compost).
Common Mistake: Baby Red Wigglers vs. Potworms
Baby red wigglers are very small. Another critter, very common in worm farms, is a potworm. They are roughly the same size as a baby red wiggler and are often mistaken for them.
The easiest tell is that a potworm is pure white, while a red wiggler, even at birth, has some pink in it.
This picture compares a small baby red wiggler (very center) next to a bunch of potworms. Note its pink hue.
Potworms can reproduce extremely quickly and have a population explosion in a matter of days. It's common for people to think they've had a massive population boom in red wigglers, but a sudden population burst of hundreds of thousands of worms like this is much more typical of potworms than of red wigglers.
Earthworm Growth
Baby Red Wigglers are very small, and can be difficult to see. In this picture you may see the worm on the right, but if you look even closer, there is a pretty newly hatched baby worm on the left.
After 40-60 days, red wigglers are able to reproduce. The worms grow bigger and fatter as they eat, becoming hundreds of times heavier than they were at birth.
If worms are not malnourished, after this time they become "clitellate." This means they now develop a visible "clitellum" which indicates sexual maturity.
Encouraging Red Wiggler Growth
Normal food waste should be enough nutrition for your worms, but if you want to give them a boost, check out Mazuri's earthworm diet - which has been custom made for worm nutrition, and will also help encourage adult worms to reproduce.
Adult Eisenia Fetida Reproduction
Sexually mature adult red wigglers are easily identified by their clitellum - the band around the earthworm's body towards their head.
Does this mean the earthworm is pregnant?
Although Red Wigglers can be "pregnant," just because they have a developed clitellum does not mean they are - it simply means they are sexually mature.
Red wigglers do, however, have a special organ called a "spermathecae." This stores sperm from previous sexual encounters and can be used to fertilize eggs inside of cocoons they will produce. Eisenia Fetida can store sperm like this for months, and maybe years. In this sense, red wigglers can be pregnant (and likely spend most of their lives pregnant). However, it cannot be discerned from visual inspection.
How Red Wigglers Mate & Reproduce
Red Wigglers, and all earthworms, are hermaphrodites! They have both male and female reproductive organs. The clitellum is similar to human ovaries as it stores the unfertilized eggs of the worm.
The male reproductive glands are on the underside of the clitellum, but are small and difficult to see.
During sexual reproduction, two worms will line up their reproductive organs to be able to exchange reproductive fluids to each other. In the second picture below you can see the sperm being transferred from one worm to the other.
Both worms will get 'pregnant' from the encounter and lay cocoons.
Worms can self inseminate, but only while trying to mate with a separate worm.
It has been documented that an earthworm rcan get itself pregnant, but it can only happen while mating with another worm and mixing up the sperm transfer. So although it can self impregnate, it still needs a mate to do it.
After the exchange of fluids, each worm will excrete mucus from its clitellum that will be sloughed off to form a cocoon, carrying fertilized worm eggs with it - just like we saw in the video at the beginning of the post.
In summary:
A cocoon is laid, and the baby worms inside develop for 21+ days.
A red wiggler hatches out of a cocoon (with 2-6 other triplets/septuplets)
They mature for 40-60 days if given enough nutrition
They reach sexual maturity and lay up to 3 cocoons weekly in ideal conditions
How Fast are Red Wiggler Reproduction Rates?
Pretty Fast.
In laboratory conditions, Eisenia Fetida have been found to be able to produce up to 3 cocoons per worm per week.
At the rate of 3 cocoons per week, and 3 babies per cocoon, red wigglers can reproduce as fast as multiplying their population by 9 times each week!
That's some serious Red Wiggler Reproduction!
Note that this is under total ideal conditions, and this level of efficiency is mostly just theoretical. Realistically, you can expect your worm population to double after 2-3 months.
(Reinecke and Kriel 1981)
Theoretical Worm Reproduction Charts
But lets have some fun with theoreticals! This is a chart representing their reproductive output assuming totally ideal conditions starting with only 500 worms.
The first 15 weeks are easy to wrap your head around. 500 worms becoming 50,000 isn't bad! But shortly after, when the growth become exponential, things get crazy.
As you can see, red wigglers doubling their population every 2-3 months is very much below their true reproductive capacity. Although this chart doesn't account for mortality, or for conditions being any less than ideal, you can clearly see that eisenia fetida's reproduction has the potential to be much more exponential than only doubling every 2-3 months.
Do Red Wigglers Reproduce less as they age?
Like most organisms, eisenia fetida will reproduce more or less efficiently depending on their age. Peak reproductive output is around the 90 day mark. Based on this study, there is a bit of a lull before another reproductive surge around day 200. It could've been conditions in the study that caused the lull - I'm not sure.
(Venter and Reinecke 1988)
Ready to get started? Our Pure Red Wiggler Composting Worms are mostly sexually mature, or nearly sexually mature red wigglers who are right in their peak of reproductive capacity!
Scott Kent
Owner of Hungry Worms. Worm farmer, soil microbiologist, and educator since 2014. Read more about me here.