Red Wiggler Eggs And Cocoons 101

Red Wiggler Eggs and Cocoons 101

Which is more bizarre?

  1. Mature red wiggler worms slide their cocoons off their heads. OR
  2. The worms inside a cocoon can survive being frozen.

There’s a lot to know about the wonderful world of Eisenia fetida and their impressive fertility techniques. This month, The Squirm Firm shines a light on the precious bundles that are red wiggler cocoons.

Little Golden Gifts

First things first. Red wiggler cocoons, those tiny lemon-shaped capsules scattered throughout the worm bin, are often mistaken for red wiggler eggs. However, it’s more accurate to note that it’s actually within the cocoon that you’d find eggs.

When I first started worm composting, I was oblivious to the tiny amber-colored gestation sacks that hid in the recesses of my bin. I’d read about them but figured my worms just weren’t making any. Eventually, I noticed the inevitable bunches of hatchlings and knew my worms were doing their thing.

When I harvested my first batch of worm compost I was elated to finally be able to get up close and personal with some of the egg sacks that had been hiding. Those cocoons are so small, only 3-4 mm long, that they are often hard to see amidst the rest of your worm compost.

Luckily, when they are first dropped, they are distinctly yellow. Not bright, but obvious against the dark rich soil of the worm bin. In time, they darken to a rich maroon color and blend right in.

“Before you use your worm compost, let it dry just enough that it will break up when sifted. Sifting the somewhat dried out compost allows the cocoons to stand out against the finely textured black gold. From there, you can just hunt and pick them out one at a time.”

Take ‘em or Leave ‘em

You may be wondering why you’d remove them at all. There are a few reasons I sometimes collect red wiggler cocoons.

For one, Eisenia fetida is not one of the native species where I live. They aren’t known to damage the ecosystem here, but can’t survive the winters. I’d rather not send them to a sure death. Instead, tucked safely inside my worm bins, each of those cocoons promises me a stronger worm workforce.

For two, I use cocoons to help balance the populations across my bin. If I have a bin running low on worms, I throw in some cocoons and expect many more mature worms in just a few months.

Lastly, it’s sometimes fun to experiment with a worm bin started from cocoons alone. Worm farmers of all ages enjoy the miracle of life and witnessing babies emerge and grow so quickly!

An Inside Look

As I sat there picking delicate cocoons from my first sifted harvest of worm compost, I noticed one seem to shake. I laid it onto my open palm in the bright light of the sun and looked closer. I could see right through that thin shell to the blood coursing through the miniature worms inside!

And then, the littlest, pink, wet worm began to poke through the opening of that cocoon! It came most of the way out then changed its mind and went back into the safety of its egg-shaped womb.

Fascinating! Seeing one hatch (almost) was all I needed to want to know all about those wee little babies and how they came to be. I knew red wigglers were well known for their rapid reproduction, but what else could I find out about those cute cocoons and the thread-like babies inside?

The Cocoon

What I learned surprised me. A red wiggler makes its cocoons in a way I could have never imagined. It begins to form as a ring around the outside of the mature worm’s body. It is made of the mucus secreted by the large clitellum gland, where some of the reproductive organs of mature red wigglers are located.

When hermaphroditic worms join to mate, they exchange sperm and begin to create this mucus ring around the clitellum. When they have finished, the mucus ring begins to dry and the worm scoots backward out of it.

As the worm slides through and out, seminal fluid, ovum, and amniotic fluid are drawn into the small capsule. It hardens and dries as it comes off the worms head, with only the tiniest hole on either end. Cool, right?

The Incubation Station

A freshly deposited red wiggler cocoon may contain as many as 20 eggs. It is inside the cocoon where some of the eggs become fertilized and some do not. Those that do begin to develop and live off of the nutrients in the surrounding amniotic fluid.

For an average of 23 days, red wiggler zygotes develop into a worm that’s ready to hatch. But It takes a special set of circumstances to call forth the next generation of red wigglers from their cozy confines into the world.

Crazy Cool Adaptations

You can hardly count on Mother Nature to serve up hatching weather every day. So, these surface dwelling worms have developed specialized survival techniques that are ultra amazing!

For one, when conditions are less than ideal, the cocoon and all its contents can just sit put and wait. They’ve been known to wait for years in fact!

Second, is a trait that works to our benefit! Red wigglers are surface dwellers, which means in nature they and their cocoons are exposed to a wide variety of adverse conditions. So, to offset a low survival rate, these worms produce relatively more cocoons than almost any other worm.

Lastly, the unique design of the red wiggler compost worm cocoon and its reproductive material is shockingly adaptive. It can even be frozen and preserved through the winter to hatch safely when the weather warms in spring!

When Worms Emerge

As temperatures rise and moisture returns to the soil, life springs back into action. Worms instinctively know when it’s time to emerge. Perfect conditions are maintained when their environment remains between 65º-85ºF (18º-27ºC) and the moisture content is between 80-90%.

But out in the wild, temperatures fluctuate far beyond this 20-degree range sweet spot. In excessive heat, worm cocoons will perish. But as I said, in extreme cold, these cocoons and all that is within them, freeze, go dormant, but do not die.

When the time is right, an average of three worms will emerge from every red wiggler cocoon.

Preparing for Your New Arrivals

Compost worms are some of the greatest pets because of how little they require in terms of hands-on care. The same goes for their hatchlings. In their modified “natural” environment of the worm bin, they have everything they need to survive and even thrive into maturity.

Remember, if the babies hatch, its because basic environmental conditions are right for those babies to survive. So, to best prepare, place your worm bin where the contents will remain between 65º-85ºF and moisture will stay near 80%.

Using a simple probe moisture meter and thermometer to measure these levels is the easiest way to be confident things are just right for nursery status. Add a bit of soft food and nature will take care of the rest.

Just make sure you’ve got enough worm bin space to handle what’s coming! If you need to, you can multiply your worm bins to allow for faster population growth.

Predicting Population Growth

For every healthy worm bin, there will be countless cocoons being formed, filled, and hatched at any one time. However, the production, rate of maturation, and survival of the cocoons very much correspond to population density, the age of the worms, temperature, moisture, and what food is available.

On average, a mature red wiggler will produce 3 cocoons per week. With an average of 3 babies coming from each of these, you can see how quickly the numbers add up. After only 12 weeks a newly emerged compost worm also becomes a reproductive member of its worm society.

Try this handy compost worm calculator to see just how big your herd can get!


Next time you’re visiting your red wigglers, get a little closer and see if you can find cocoons that are new, old, and even already empty! It’s fun when you know what you’re looking for and what’s inside!

For more exciting red wiggler discoveries, sign up for our newsletter. Of course, it’s FREE and only comes once each month. Inside you’ll find timely tips, fascinating creature features, and practical advice for everyday worm composting.

Happy worm composting!

Readers Comments (20)

  1. I’m having a heck of time with fruit flies in the bin. Every time
    I open the lid I realize hundreds. I bought some fruit fly traps that
    seem to be helping. One thing I’ve noticed is a covering of what looks
    like sand grains on the inside of the bin. What could these be?

    • Hi, Elaine Robin.
      I’m sorry to hear about the fruit flies. The hose attachment on the vacuum is a great fruit fly weapon! Aside from that- if you can hold off on any more fruit or veggie feedings until they are all gone- you can start fresh. Your worms can eat moist cardboard or newspaper for a bit, right?
      As for the sand looking something on the side of your bin- that could be mold, fungus, or possibly eggs of some sort- but not fruit fly eggs. Check out our article on Fruit Fly Invasion to learn more!…-bin-we-can-help/

      • Another way to avoid fruit flies is to freeze all the food material before you put it in the bin. Easy way to do this is to collect your compost stuff in a bag in the freezer until you have a full bag, then put it in the bin.

  2. How come I never catch my worms producing c cocoon? I have seen the babies emerge from the cocoon. I even have a video of a baby emerging almost all the way out, then changing its mind and going back in.
    My worms produce 2 sizes of eggs. Some eggs are 3-4mm long as described in the article but others are just 1.5mm long. Are they from different kinds of worms? The small ones produce just one baby, as far as I can tell.
    Another thing, the babies from the larger cocoons do not emerge all at ones. Sometimes it is several days in between. Is this common? I’ve never seen this mentioned.

    • I read somewhere that smaller but mature worms get smaller coocons, maybe containing fewer eggs.

      • Hi Paul. That’s interesting! I haven’t seen that butI’ll look into it. Feel free to share the source if you happen to come upon it! Thanks!

    • Hi Jennifer. Great observations! And I found the same to be true- only once have I thought I saw a cocoon come from one of my worms. ? Not sure why when it is happening so regularly.
      As for the different sized cocoons in your bin, we could assume that those would come from different species. But which?
      I’ve also seen my worms go most of the way out of a cocoon only to reverse their way right back in. I guess they can test the waters, so to speak, and change their mind if they don’t want to leave yet.

  3. I,ve been watching some utube sites, which all seam to come from warmer places. They advise you to give your worms a shower now and then. As i live in England im reluctant to do this at this time of year. What is the best thing to do?
    Love this site so much infomation.

    • Hi, Leslie! Thanks for sharing what you’re seeing and asking when you aren’t sure!
      So, let’s think about this, a shower for your compost worms. You might do that for a couple of reasons. The first is simply to help regulate the moisture content of your bedding. It should be pretty high (80%), so a shower may make sense pretty regularly if you live in a very hot and arid climate. OR a shower could be intended to create something of a compost tea which the owner wants to collect for some reason. OR you may find that an ant infestation would be mitigated by a “flush”, if you will.
      However, if you are able to maintain your worm farm without regularly adding water, then you’re doing great as is.

  4. I think my worms stopped laying eggs 4 to 6 weeks ago. I live in Northern Virginia but the worms are inside in a closet and the temperature shouldn’t vary by more than about 2°. Do they slow down in winter? How would they know what season it is? What other reason could there be? Maybe it is getting crowded. They love their food (foodprocessed fruits & veggies, frozen, then thawed). They look very healthy.

    • Hi, Jennifer! I’ve always believed that it was strictly temperature that tips such creatures off to the arrival of winter- especially when they are kept fully in the dark. So what could it be? Yes, they do slow down in the winter- but because of the cold. If they are close to “normal” room temperature, they should be unaffected by the 2-degree change. Other reasons have to do with moisture content of the worm bin, pH, population density, and amount of food available. If you want to give them a test, you could transfer some worms and bedding to a new and empty bin to see if they quickly get busy to fill it up. I hope your mystery is soon solved!

      • I figured out why they stopped laying eggs. They wanted new bedding. As soon as I gave it to them they started laying eggs again. The new eggs seem to take much longer to hatch. And a number of those big 4-5mm eggs are yielding single babies. One of the biggest eggs, or cocoons rather, I ever saw hatched a single baby that was so fat! Rather than being uniform in size throughout the body, it had a larger middle, like a fat belly. It was so cute.

        • Hi Jennifer, thanks for letting us know what you figured out! That’s so cool and great for us all to keep in mind. Our worms really love fresh bedding to be added pretty regularly. Something to add to your spring cleaning list? I’ve gotta say though, it sounds like you have a different type of worm than red wigglers in there! I’m jelly, I wish I saw that cute fat worm baby you got to see emerge!

  5. Is it possible to add a picture with a comment? I have a question but need to show a pic to ask it. How do i do it? I am doing it from my phone.
    If anyone would like some free worms for composting and are close to Reston, VA, let me know. I am pretty sure they are a mix of different kinds because some do not look alike.

  6. I have red wrigglers and night crawlers in the same bin. Is this a problem?

    • European Nightcrawlers and red wigglers CAN coexist. Tolerant of similar conditions, these two work side by side without much fuss.

  7. Searched worm eggs and found this site. Here’s my story I live in the city and the neighbors wanted to clean out the alley, in front of my alley door plastic bags and other trash piles up every year. While cleaning I heard look at all the worms I shout don’t kill them throw them in the garden. That was last year I don’t know if they took my advice since I had to leave.

    This year I cleaned out the alley myself moving the plastic bags with a gentle hand hundreds and hundreds of worms. I grabbed a shovel plus two 5 gallon buckets. Filled the two up plus two bags with black gold and worms. I now have a thriving worm farm been feeding them for a month now.

    Worms will find a home without the help of humans.

    I’m now making tea and the plants love it. I’m addicted thanks for putting this site together I learned a lot from it.

    • Hi Timothy. I’m so happy to hear you are enjoying a thriving worm herd. I’m so curious about what type of worms they are and what drew them to the plastic bags. Nice save, by the way!

      • Hi Francesa, Happy is an understatement. They are for sure red wigglers they been doing their thing forever since I own the house. I live in the city of Philadelphia my yard is the end of the alley.

        Weeds, elephant plants and whatever grew back there would be the worm food, when the winter was coming I was stepping on them its easy to clean them up which I never did.

        I had a giant building behind my house that belongs to the National Guard called the Army that building blocked all my sun.

        Sad to say they torn that building I guess I can say its good for me so I got back into gardening.

        The plastic bags, not the other trash as I stated it wasn’t a dumping ground the plastic bags would float there from human pigs landing there just like in front of my house.

        The plastic bags worked the same way as leaves holding in moisture to give them the environment they did.

        I did encounter one problem from this natural worm farm was Cent with the all the legs funny I can’t remember how to spell it. I’ve been picking them out and throwing them into the rainwater.

        I started moving the worms into bins to control them Peace out.


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