Question from Mike F:
I have been composting for a few years now. I want to start composting
with worms. I have a large compost pile that I put everything in that
does not fit into my three other compost bins. I was digging in that
pile just to get a little extra air into it and found thousands of
worms. My question is are those the right worms for composting in a
worm bin, or should I just buy some ?
Great question! You’ve actually (accidentally) hit on a great way to test if there are “epigeic” (will get back to this term in a minute) worm species in your area. All you need to do is lay down some rich organic matter, such as farmyard manure (the real stuff – not from a bag) or food scraps mixed with shredded newsprint (good idea to cover this with something like straw) etc, keep your heap moist, then simply wait.
Getting back to the term “epigeic”…
There are three primary categories of earthworms based on where in the soil profile they live. Briefly, the “anecic” worms are those that create very deep vertical burrows, really only coming up to feed and mate (or to escape flooding). “Endogeic” worms are the “in-betweeners”, creating horizontally-oriented burrows in the soil zones closer to the surface – these would include most of the small to medium sized species we might think of as “garden worms” encountered when digging around in the soil. Lastly, the “epigeic” species are those that live very-close-to or – very often – actually above the soil surface in rich deposits of organic matter (eg. old manure heaps). As you’ve probably gathered by now, these are the ones we are after. Apart from being adapted for life in rich organic matter (and of course having the ability to convert these materials into rich worm castings), they can also breed much more quickly, and tolerate higher temperatures and crowded conditions.
SO, any time you find loads of one species (often fairly small – but not necessarily) throughout your compost heap (or test pile), there is a very good chance you’ve found a species that can serve as a valuable “composting worm”. Endogeic – and even anecic – worms will often be found in or near composting systems as well, but they tend to remain close to the soil/compost interface, and you will almost never find any one species in huge abundance.
There ARE some semi-soil worms – what you might refer to as “epi-endogeic” or “endo-epigeic” species – that can seem like composting worms (venturing further up in the heap, and in greater abundance), but they will almost never occur in the same sorts of densities – or be as widespread in the waste materials – as the true epigeics.
Based on that you’ve described, Mike, I’d say you are probably fine to leave things as-is. Perhaps some Red Worms have traveled from a neighbor’s compost bin and invaded your heap? You might try collecting some of them and start up a small worm bin so you can observe them more closely. If they thrive in the bin environment (increase in number and process wastes) you can pretty well guarantee that you are good to go!
Hope this helps!