Why Are My Worms Still Roaming?

Question from Steve:

I have to keep a 2 watt led bulb in my bin to keep the worms from exploring our basement. I’ve had them for 3 months now and I would have expected them to settle down quite a while ago. Any ideas?

Hi Steve,

There are a number of factors that can contribute to the likelihood of worms roaming. Let’s take a look at some of the main ones.

1) Worm Species – different species of composting worms have different tendencies to roam. Red Worms (Eisenia fetida/andrei) are, in my experience, the most mellow among them. Once they are settled in they seem to be the least likely to roam excessively (in enclosed plastic bins they will often roam up the sides a bit – but won’t typically try to escape).

European Nightcrawlers (Eisenia hortensis) will also be fairly mellow once settled in, BUT are far more prone to roaming when they are disturbed than Red Worms. Digging around, adding food/water, even just bumping or sliding the bin can result in quite a few Euros wanting to make a break for it.

Blue Worms (Perionyx excavatus) are notorious for their roaming behavior. They don’t necessarily just stop at leaving the system either – people have found them up on their walls, and who knows where else! I’ve read reports of them being found up in trees and even on top of office buildings – so climbing is definitely part of their nature. The thing about Blues is that they can be a very common invader of Red Worm cultures – and some worm farmers even sell essentially pure Blue Worm cultures as “Red Worms”. So a LOT of worm composting folks have them without even realizing it.

I haven’t worked with African Nightcrawlers before, but I’ve read that they can be prone to wandering at times – due to disturbance or as a result of ambient conditions.

2) Age of System – as a system matures and the proportion of worm castings increases, the worm habitat quality tends to decline and this can lead to what I refer to as “mature worm bin syndrome”. Often out of the blue, the worms will just start trying to escape – or they may even start dying off. One thing that can accelerate this is the practice of continuing to add food wastes without adding any absorbent, carbon-rich bedding materials to balance things out. Also, just generally, this can happen when you leave the system going for months on end without harvesting any vermicompost.

On the other end of the time scale, a brand new system can also stimulate roaming (this is likely when new vermicomposters will encounter the most roaming, in fact). The worms are often not used to their surroundings (they don’t feel like “home”), so they don’t want to stay put.

3) Ambient Conditions – if it is dark, warm and humid or wet in the environment surrounding the bin, the worms will be far more likely to venture out from the system. If, for example you have a bin sitting outside in a warm, rain storm (especially at night time) – there is a very good chance that quite a few worms will be inclined to leave – especially if the system has some means of escape at the bottom. But even a system sitting in a humid/damp, dark basement would be more likely to have roamers.

4) Food/Bedding Added – as you might guess, adding food and bedding materials that are harmful (or at least lead to harmful conditions) can make worms want to leave the system. Examples would include any materials that contain inorganic salts or chemicals (eg salty foods, potting soil with fertilizer in it), or that give off ammonia gas (eg fresh manure).

5) Handling/Disturbance of the System – as touched on earlier, some worms are particularly prone to disturbance. So when working with these species it is important to leave the worms alone as much as possible.

Based on the information you shared, it’s hard to say for sure which particular factors are responsible for your worms desire to roam. One suggestion I would have (assuming you’re not already doing so) is to keep a nice thick layer of dry bedding over top of the composting zone. This offers a double benefit of A) reducing moisture levels on the upper walls and underside of the lid (making it less appealing for the worms), and B) providing you with a continuous supply of bedding to mix in with your food (to help prevent the “mature worm bin syndrome” I touched on).

I actually like your 2 watt light approach. Obviously it doesn’t use up much power, and if it works to keep them down that’s great!

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    • Steve
    • May 9, 2015

    Thanks, lots of good info. I have European Night Crawlers and I have been aerating once a week and feeding in smaller batches than necessary. I think less feedings with more food and less aerating is something to try. I also do not have a dry layer of bedding on top. That’s also something I will do. I don’t mind paying for the 2 watt light but it would be nice to not have to use any electricity for the worms. I do get a lot of interesting mushrooms though.

    • Bill Braun
    • May 13, 2015

    To Bentley’s comment on bedding I’ll add, after ruling out harmful stuff, double or triple the amount of bedding, see if that helps. I have Red Worms in a Worm Inn that sits in the dark and I never have runners.

    • Bill Braun
    • May 13, 2015

    Ah, reading further I see he already covered that ground. So, I cast a vote for his response.

    • Bentley
    • May 13, 2015

    You actually reminded me of another important point, Bill (thanks)! With extreme air flow (such as with open systems and Worm Inns) – assuming the system is in a fairly dry location – it is far less likely worms will roam. Although, with a Worm Inn what you need to watch for is worms coming out the bottom if you are letting it stay too wet down there.
    Overcrowding is another potential reason worms roam that I forgot to mention.

    • Steve
    • May 13, 2015

    Putting dry bedding (sawdust) on top took care of the problem. It’s been 4 days with no light and none of the worms seem to be getting a case of wanderlust. Thanks for the tips.

    • Bentley
    • May 13, 2015

    That’s great, Steve!
    Thanks for the update.

    • steve
    • May 13, 2015

    Wow, I noticed another benefit to the sawdust on top. The room temperature didn’t change but the compost temp went from 62 to 70 degrees. I just added some compost and as soon as I started making a trench I could tell the compost felt warmer. The worms seem more active when I dig the trench but they are still staying below the sawdust barrier.

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