Blue Worms vs Red Worms & Euros

Good question from Judith:

Could you elaborate on the “blue worms” – you say they are good composters, but seen as pests. Why would we not want them? Do they take over? What is the down side of them in the bins?

Hi Judith,

Blue Worms (Perionyx sp.) grow quickly, produce lots of offspring, and consume lots of waste materials when conditions are favorable for them. This is what makes them a great composting species. BUT in these situations (when conditions are favorable) they can also basically take over systems where other worms, such as Red Worms or European Nightcrawlers, are present. SO, you may see the numbers of these other worms gradually decrease over time.

In cases (usually in warmer regions) where worm farmers are trying to grow pure cultures of Reds or Euros, it can (understandably) be frustrating when Blues infiltrate and become established. This is why many people refer to them as “pests”.

Temperature is probably the main factor of importance. Temps between 70 and 86 (~ 21 C and 30 C) tend to be very favorable for Blues, and it’s when a system is in this temperature range for extended periods that the Blues tend to dominate.

On the flip-side, these worms also tend to be pretty cold-intolerant. Down below 70 F (~ 21 C) or so, they can really slow down and become far less effective for vermicomposting – and they’ll usually start to die once temps drop down below 50 F (10 C). This can be frustrating for those living in cooler regions (vermicomposting outdoors), since it can become necessary to replace your worms periodically.

Red Worms and European Nightcrawlers remain effective at lower temps (than Blues), and will basically only die if they freeze solid.

Blue Worms can also be somewhat temperamental – prone to roaming – even outside of the system – without much warning (whereas Red Worms and Euros tend to be more mellow – although Euros are a fair bit more temperamental than Reds). Various factors, such as a change in weather, excess watering, hunger etc can be responsible for this.

Bottom-line, it all comes down to your overall goals and tolerance. If you are planning to keep your system(s) in a climate-controlled location (with warm temps), and are keen to quickly convert as much waste into castings as you can, Blue Worms are a great choice. And lots of people swear by them (while others swear AT them – haha).

If, on the other hand, you’d prefer a more “mellow” worm and/or your system(s) will experience fluctuations of temperatures (and conditions in general), you are likely better off to go with Reds or Euros.

As far as Blues that hitch a ride in Red Worm or Euro cultures goes – my advice is not to worry about it TOO much. Not every batch of Reds and Euros has Blues, and even when they do, they tend to make up a relatively small proportion of the total population.

(Except in the case of suppliers that sell 100% Blue Worm cultures as “Reds” and “Euros”…grrr!)

Whatever your final conclusions about all this end up being, I highly recommend learning how to properly identify the common composting worm species (the Red Worm Composting Facebook group is an excellent place to learn more about this and ask for help with worm IDs).

Hope this helps!

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    • Judith
    • August 2, 2015

    Thanks for the answer, Bently. I have a large, 4′ x 8″ heated bin in a barn, so if I inadvertently introduced the blues, I would probably have to let it cool down (in Colorado high country that’s not hard to do!) to “take out” (as in “I took Cecil the lion”) the blues. The bin seems healthy, but has been neglected, and I think I underfed. There are worms, that appear healthy, but not the masses I would expect to see. I now have a new supply of aged horse manure, and a steady supply of coffee grounds, so want to up the activity. Would you suggest buying a new supply of worms, or let the present ones reproduce at their own speed? The vermicompost is wonderful, and though I intend to sell it, I put the first half of the bin on my own gardens – couldn’t resist.

    • Bentley
    • August 7, 2015

    Hi Judith
    Sorry for the delay. My recommendation is always to optimize for the worms you have, rather than just adding more. If they are not at the densities you would like to see it means optimal conditions haven’t been achieved. Are you mixing in moistened bedding materials as well? Is the bed fairly moist in general?

    • Michael Schuette
    • September 20, 2016

    Dear Bentley,

    I am 68 years old, partly walking impaired but still want to do something. I discovered the garden tower project 2 and like to start ih it in my community – in Indonesia, where I seee many chances to help improving peoples lives. However I am facings ome problem: nobody has worms to sell here, so that I was thinking of getting some “blue” one, because of their highter resistance to heat. I would suggest we send them to Singapore (friends address) because of far faster arrival, from there they could be picked up within a day from myself.
    Could you kindly help me and letting we know how much 1 lb. would cost incl. US priority mail. Of course for this first transport I would take all the risk, even if they would all arrive dead, I would never complain – but better trying than doing nothing!

    For your help in advance my sincere thanks
    Michael schuette, / Batam (indonesia)
    PS: this is not a comment but a cry for help!

    • Bentley
    • September 30, 2016

    Hi Michael
    I don’t sell Blue Worms – and also don’t ship internationally. But I bet you can find SOMEONE over in that general vicinity who is vermicomposting with them, even if you can’t find a specific supplier. Google is an amazing tool – just do a variety of searches. A basic “indonesia, vermicomposting” search led me to this link:

    They may be able to help you find composting worms. Dig around – I guarantee there are others in that part of the world who are vermicomposting and who could potentially help you get some worms.

    Good luck!

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