Composting Worms vs Soil Worms

Question from Christine:

I have been composting with worms for quite sometime now, and I have a
question that no one seems to have the answer to. I want to know why
they say to use red worms as opposed to earth worms for composting? I
have so many earthworms and would like to use them, so why do you
recommend red worms instead? Please let me know, thank you, chris

Hi Christine,

In a typical backyard composter (or composting heap etc) that’s in direct contact with the soil, regular soil worms will certainly come up into the lower reaches of the system and process the wastes – but it’s very important to realize that soil worms are NOT well-suited for composting at all, in comparison to varieties such as Red Worms.

Red Worms are among those earthworms known as “epigeic” worms – that is to say that their natural habitat tends to be near or even above the soil surface. They are specialized for life in rapidly changing environments – specifically, rich organic matter deposits such as manure heaps and compost piles. They can tolerate warmer conditions and much higher worm densities. They can also breed and consume wastes much faster than typical soil worms (which are classified as either “endogeic” or “anecic”).

In indoor systems, it’s actually next to impossible to keep and breed most soil worm species – at least when using your typical indoor worm composting bins/beds – so Red Worms (or other composting varieties) are always going to be your best choice when you are specifically wanting to process wastes materials quickly and effectively.

Hope this helps!

P.S. You may also want to check out this post to learn more about the different worm groups: Attracting Compost Worms in Your Backyard

P.S.S. The term “earthworm” refers to all three groups (mentioned above), including all composting species (even though they usually don’t live in a purely soil environment).

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    • Debora
    • February 27, 2012


    I am just getting started with my own worm composting bin, and I too was surprised that I couldn’t just harvest the worms from my own yard. So could you please elaborate on the differences presented in the following questions.

    If a person is adding fresh horse or cow manure to their backyard composter is it reasonable to assume they have epigeic worms in their compost pile?

    And, other than purchasing epigeic worms, where would one find epigeic worms in the wild?

    Also, if one might find endogeic worms in their outdoor composter, why wouldn’t they survive an indoor worm bin? I understand that they won’t be as efficient as epigeic worms, but why wouldn’t they survive?

    Thanks, Debora

    • Bentley
    • February 27, 2012

    Great questions, Debora!

    If you add manure to your backyard composter, and there are worms already in it, OR someone nearby happens to have Red Wigglers (etc) in their composter – there’s a decent chance you could end up with them in the system. That said, you certainly won’t always find them in manure heaps – nor will you necessarily be able to attract them to your bin (if there are none in the area).
    If you DO end up with a lot of worms in your composter and they seem well-distributed throughout the system (not just down near the bottom), perhaps you do have another type of epigeic worm.

    There are various types of epigeic worms – and not all of them are necessarily top notch composting worms. You can find some of the other varieties in leave litter and other rich deposits of organic matter. Red Worms don’t really live in “the wild” per se – they tend to be closely associated with human activities – most commonly occurring in old manure heaps etc.

    Endogeic worms are adapted for live in soil, so the rich organic matter in a worm bin (and no soil) wouldn’t be favorable. They also need some space for their tunnels, and likely prefer somewhat cooler temps. My guess is that they would be easier to keep in a small indoor bin/bed than anecic worms (the deep burrowers) – and I’m sure it wouldn’t be hard to keep some alive for quite some time. But the likelihood of them actually thriving (let along being good composting worms) is very slim.

    • Shay Madel
    • February 29, 2012


    Love your site, but I want to encourage you to be clear and generous with your comments about nightcrawlers, or other non-epigeic worms.

    Red wrigglers are the worm of choice for quick, contained composting. They are wonderful.

    HOWEVER, my grandparents, who farmed organically for about 50 years had loads of nightcrawlers in their compost pile. They would laugh to hear this discussion.

    If you already have nightcrawlers around there is no reason not to move some to your outdoor compost pile. They will probably find it on their own, anyway. If the pile is good for them, they will eat it up, and at other times of the year or decompostion cycle they will squirm back into the ground. Everything helps out, even if it doesn’t win the composting race.

    • Linda
    • January 19, 2014


    I live in the Pacific NW – USA and am trying my hand at winter gardening (with the typical salads and winter veggies) in a small glass greenhouse with lights (ceiling) and 60 degrees heat. My plants are not thriving… in fact, they are dying.

    When I planted the 6”-9” deep box, along with many tall gallon (or larger) pots, with new potting soil mixed ½ and ½ with new bagged compost, I placed a thin layer of not-quite-composted alpaca manure in the bottom of each container. This manure contained composting red worms.

    Are they eating the roots of my young plants? I know earthworms will leave the plant roots alone, but red worms are SUPPOSED to eat all living material. Do you suppose this was my mistake?

    Maybe the manure was still too hot? (although it no longer smelled, yet was sorta crumbly)

    Linda Fox
    Vashon Island, WA

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