Which is more bizarre?
- Mature red wiggler worms slide their cocoons off their heads. OR
- 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?
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!
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Happy worm composting!