Symptoms of a ‘Sour’ Worm Bin

Half an avocado absolutely coated with white mites

Well, it seems my experiment with adding bokashi to an indoor worm bin has ended up having semi-negative repercussions. I just HAD to add that second helping, didn’t I?

For some reason, seeing that the worms were finally moving into the material inspired me to push my luck by adding even more. Unfortunately, that ended up causing what people commonly refer to as a ‘sour’ worm bin. Truth be told, I am actually quite happy about it, since it provides me with the opportunity to experiment with getting things back on track in the bin, and should be a valuable opportunity for learning (both for me, and for those reading the blog).

So how do I know that all is not well?

One obvious indication is the unpleasant odour that greets my nose when I open the bin. I’m not sure how to describe it – it’s not the typical smell of rotten food waste, and it’s certainly not the nice earthy smell of a properly balanced bin. It’s more like the smell of badly spoiled milk, and makes me understand why people refer to it as ‘sour’.

I’ve also noticed a massive increase in the populations of white mites and white worms. The mites are coating everything. As I’ve written before, the mites themselves are not ‘bad’ or ‘harmful’ – but when a population explosion occurs it typically is an indication of a pretty major shift in the balance of the bin. Generally it occurs when excess food has been added and when conditions become more acidic (the two often go hand in hand). Large amounts of food clumped together can easily go anaerobic, producing acids and alcohols (among other things).

Just the amount of waste I added (too much!!) was bad enough – but what made it worse was the fact that the material was already anaerobic since it had been fermenting in the bokashi bucket. As mentioned, everything was totally fine after the first addition of bokashi scraps. After a few days I could smell that aerobic conditions were getting re-established, and the worms were readily feeding on the materials. At that point, I should have simply let them continue processing that material for awhile before adding any more!

Interestingly enough, I added a LOT of bokashi waste (probably 4 times as much) to my outdoor composter a little while ago and it was full of worms very quickly! Certainly an indication that the size of your system can have a major impact on its ability to handle various waste materials.

One other indication that something was ‘off’ in my indoor bin was the behaviour of the worms themselves. Like I said, they had moved up into the first layer of bokashi waste and seemed to be actively feeding on it. Once I added more however, they were suddenly nowhere to be found. Digging down I can find them below, but they definitely seem to be avoiding the upper layers of the bin!

I must say I’m pretty impressed with the tolerance of these European Nightcrawlers though! I suspect if this had been a Red Worm bin, I might have at least a few dead worms (or worms attempting to escape) on my hands.

As far as trying to rectify the situation goes, I’m definitely not going to doing anything drastic, like add lime or anything like that. I want to gradually shift conditions in a positive direction, not throw things completely off-kilter! I think the addition of a thick layer of fall leaves, shredded cardboard and ground up egg shells will be a good start.

I’ll be sure to keep you posted on my progress!

[tags]worm bin, sour worm bin, anaerobic, bokashi, vermicomposting, worm composting, food waste, european nightcrawlers[/tags]

**Want Even More Fun With Worms? Sign Up for the RWC E-mail List Today!**
Previous Post

Fungus Gnat Invasion

Next Post

Teenage Mutant Ninja Red Worm!


    • Alison
    • April 19, 2008

    Hi Bentley, I tried to get some of my bokashi out from the bottom of my bucket to give to my worms but it stank so bad I trashed the lot.I put it behind my composting area and everytime I went there for ages the foul smell was too much.So my first try was a total waste of time and very discouraging but I shall probably try again.

    • Bentley
    • April 23, 2008

    Hey Alison,
    Sorry to hear that. I remember you mentioning that you hadn’t kept your bokashi compost in a tightly sealed container. I wonder if this had an impact. I noticed that the material in the bin with the loose-fitting lid smelled more like an anaerobic mess of food scraps than the other bucket (which had the sweet bokashi smell).

    Anyway, let me know if you try it out again.

    • Tracy
    • April 23, 2008

    Hi Bentley,
    Well I am now scared to put mu bokashi in my worm bin! I have a pail that has been fermenting for about 4 weeks. Do you think maybe I should just put a small amount in or any ideas on how I should go about it. My worm bin is the standard Rubbermaid tote “deluxe” setup that you had on your video. The worms have been in there since Feb are are doing well.


    • Bentley
    • April 24, 2008

    Hi Tracy,
    You don’t need to be too scared – just make sure you do so in moderation. Start with a very small amount and see how they respond. Don’t be a dummy like me (haha) and go overboard with it. I’d also recommend adding some fresh bedding first to help provide a bit of a buffer zone.


    • Annelize
    • September 11, 2009

    i have got very small red orangy bugs in my wormfarm it seems they are eating the worms please advice.
    i bought some worms and divided them into four bins but only two of them has got this bugs in and it seems that the worms is escaping.

    • Bentley
    • September 11, 2009

    It’s hard to say for sure what they are without seeing a picture. I suspect they are some type of mite. There are very few species that harm worms, but those that do are apparently reddish in color.
    If the worms are trying to escape (and are dying), you may have something else going wrong in your bin altogether, and the mites could simply be feeding on the dead/dying worms.

    • rusty
    • January 23, 2011

    I can spinkle some worm feed in my bin and in about 2-3 days it will have hairy mold on it?Good or bad?What do i need to do?these are new plastic bins with good air flow.

    • suzan
    • December 25, 2011

    This is the second time I’m writing for help. After i got the redworms, a month later the bin got anerobic, too wet & sticky, even though i wasn’t adding more water. I might have had too much food in the bin, those creepy little white worms [potworms i think they’re called] & some brown mites,very small, were everywhere. I felt bad moving the worms to a new bin, since they had started making a lot of compost. But about half of them,or less, were still alive. Now I’ve been so careful about everything & this new bin, one month old, is also becoming wet & sticky, not really smelly, but the white worms & mites are coming back by the ton !! I find several worms on top of the bedding in the mornings, but only 1 or 2 escape down in the bottom pan daily. I think maybe the bedding is too acidic, even though i have a lot of crushed eggshells in the bedding. I put about a tsp of coffee grounds in every 10 days. and feed them about every 10 days as well. I just don’t know what to do. Bently, I would appreciate any suggestions you might have. Thank you, Suzan

    • Bentley
    • December 27, 2011

    Hi Suzan,
    The best way to reach me with questions is definitely e-mail (I can be slow, but I do usually get back to people – comments a lot less predictable).
    My suggestions (you certainly don’t need to use all of them) for wet bins is 1) adding dry bedding, 2) leaving the lid off for periods of time each day, 3) drilling more holes, 4) harvesting and starting a new bin (if the bin contains a decent amount of dark compost). I would also suggest stopping feeding altogether for a little while.

    • Suzan
    • December 27, 2011

    THANK YOU Bentley, I will take your advise. and what is your email address??

    • Bentley
    • December 27, 2011

    No worries, Suzan – just look for the “Contact Us” link in the upper navigation (and don’t get scared off by the stuff about me maybe not being able to reply etc)

    • Leslie Patterson-Werner
    • January 17, 2013

    All of a sudden I have lots of white mites. I forgot what to do. Add coffee grounds? Add crushed eggshells? Leaf matter?

    • shane
    • November 19, 2018

    was wondering what happens when you change worm farms and dump worms and bedding in new farm and bedding buries worms?

    • Bentley
    • November 29, 2018

    That’s no problem at all, Shane. Worms are used to being buried. 🙂
    As long as the habitat in new system is good you are all set.

    • Tracy
    • January 10, 2019

    Hello Bentley
    I am new to this worm farm business. I am learning a lot. Thank you for your information and everyone else for their questions.
    Here is my question…..
    How much mold is to much? I have a container that had the top 3/4 filled with mold. My worms are huddled under the cardboard container I have in there. It now looks like 90% castings under the mold. The underside of the mold is colorful but I see no mites or whites worms. Do I add more paper, bedding and waste? Make a new bedding for them? Or leave it and see what happens?
    Looking forward to hearing from you.

    • Bentley
    • January 13, 2019

    Hi Tracy
    You literally have 3/4 of your bin filled with fungal mold (not leaf mold, right)? If so, that tells me you are likely overfeeding and likely not putting in enough bedding materials. Not sure what you mean by “cardboard container” or why it would be in there, but I would recommend mixing in a lot of somewhat moistened shredded cardboard. Nothing really wrong with the mold – but it is best that it get broken up and mixed in with everything else – that way the worms can likely just consume it. Go light on the feeding for a while. Things should start to get back into balance fairly quickly.

Leave a Reply

Your email address will not be published.

Get Your Free Vermicomposting Guide!

* Join the Red Worm Composting E-Mail List Today *