Red Worm Cocoons
As mentioned in my last post, I wanted to write something about red worm cocoons and post some pictures so that everyone knows what they are looking for.
The other day when I was digging through one of my bins I came across an unbelievable mass of cocoons (also called ‘capsules’). I usually have no trouble finding them in any of my worm composting systems, but I can honestly say that I’ve NEVER seen anything like this.
Unfortunately I could not get a good picture (camera didn’t know what to focus on) but I figured I would post the best one anyway.
I also took a much better picture of some cocoons I collected. As you can see below, worm cocoons have an oval or even tear-drop shape to them. They tend to be a dark straw-yellow colour, but become darker brown once the young worms hatch.
The number of cocoons in a given worm bin depends on conditions and materials present. I’ve seen major increases in cocoon production in paper sludge, and you’ll often find a lot of eggs associated with corrugated cardboard if you happen to use it as bedding.
Temperature, moisture content and worm population are all important determining factors. If conditions in a system decline – food source depletion, drying out of bedding, temperatures drop etc – red worms will often start producing more eggs to ensure the success of future generations. I’ve read that some worm farmers will actually dry out their systems in order to get increased cocoon production (and then will bring moisture levels up again to stimulate hatching).
Worm cocoons can withstand conditions far worse than those tolerable for the worms themselves. Glen Munroe reports in the Manual of On-Farm vermicomposting and Vermiculture that red worm (Eisenia fetida) eggs can even survive extended periods of deep freezing.
Cocoons can also remain viable for many years before hatching. Vermicomposting expert, Dr. Clive Edwards has heard of worm cocoons being able to survive for as long as 30-40 years (Casting Call, Vol 2 #6; p1).
The cocoon itself starts as a mucus band produced by the clitellum during reproduction. Once sperm is exchanged between worms (remember each worm has both male and female sex organs but most species still reproduce via cross-fertilization), the worms separate and the clitellum releases a compound which causes each worm’s mucus ring to harden. This hardened band is then slides off the worm, collecting sperm and eggs along the way. As it separates from the worm both ends are sealed.
One other little tidbit of interesting info…
I’ve read that worms hatched from cocoons in a given material will tend to be much better adapted than any adult worms introduced to the same material (assuming they weren’t also born in it themselves). If you buy worms that were raised in manure and try to feed them food scraps for example you may find that they want to roam initially (I have witnessed this myself). Adding a bunch of cocoons on the other hand should provide you with a thriving population of highly adapted worms (assuming you don’t mind waiting for them to hatch and grow up).
I’m actually surprised that more worm sellers don’t offer cocoons – they’d certainly be much cheaper to ship and could potentially result in more bang for your buck (each cocoon of Eisenia fetida will generally produce multiple baby worms).
Well, I think that’s enough about worm cocoons for now! If you have never seen any yourself, be sure to dig around in your bin and see if you can locate some.
My next goal is to see if I can get a picture of a cocoon with a baby worm coming out. I’m going to try hatching some outside the bin in a smaller system where I can keep close tabs on them. I’ll be sure to keep you posted on my progress!