Do Worms Eat Microbes or Wastes or Both?

Really great questions from Sherman:

Hi, I read that red wigglers consume microorganisms rather than food waste so how does having more worms consume food wastes faster?

What types of kitchen food waste’s good for supporting the microbial population?

Hi Sherman,

Thanks for writing in – this is a really interesting topic for discussion for a number of reasons.

OK – let’s start with microbes as worm food…

Yes, it has been shown that worms derive much of their nutrition from microorganisms that have colonized decomposing organic matter. I think part of the problem here is that these worm composting facts – in this case legitimately based on actual scientific research – can be viewed in too-rigid a manner. i.e. Worms eat microbes, that’s all they eat, and THAT’S THAT!!

While I would absolutely agree they likely get most of their nutrition from all those microbes – the fact is, they are definitely consuming more than just microbes (thereby getting nutrition from more than just microbes as well).

The microbes are using enzymes to break down the food materials – in the case of fruit and vegetable wastes, for example, this would involve the rupturing of cell walls, and the release of water (along with plenty of nutrients for the microbes to “feed” on). So you kinda end up with this slurry of stuff (for lack of a more scientific term – lol) that’s full of microbes.

Well, picture the worms coming along like a Hoover and sucking up this slurry, microbes and all. Yes, much of the nutrition will be locked in the microbes themselves, but there’s no doubt they are ingesting a lot of the waste material as well.

It’s as though the microbes are softening the food for the worms, and the worms are saying “thanks” by eating them. lol

OK – on to worm numbers and how that affects processing speeds…

In theory, if there are more worms there are more “mouths to feed”, so more wastes can be processed. In a well established system, using foods that have been well-optimized (i.e. made even more microbe-and-thus-worm-friendly), this can definitely be the case. But the problem is that people (often newbies) tend to take this too literally – assuming they can start a system with loads of (usually poorly optimized) food wastes and loads of composting worms, and that everything will work out great as a result.

Unfortunately, that’s very rarely how it will actually work. What usually happens in cases like that is that the food wastes become foul, heat up, give off toxic gases etc, causing the already-stressed worms to either die or attempt to escape the system.

My recommendation is always to start with a modest population of worms, and modest amounts of optimized food materials (along with plenty of bedding), and to gradually ramp things up from there. These worms will grow and reproduce very quickly when they are provided with a scenario like this – and you can end up with a large, thriving population of worms that CAN process lots of wastes quite quickly.

Let’s talk briefly about kitchen scraps…

Obviously, the usual composting rules aside (i.e. “no meats, dairy etc”), ideal kitchen scraps are those that come from water-rich foods (fruits and veggies), and that have been optimized for microbial colonization. Something like a whole carrot, for example, is pretty much useless as a worm food. For one thing, it’s a root vegetable so it is designed for life in soil! If anything, it would probably start growing in your worm bin. lol

When you chop, freeze/thaw, cook, age etc resistant wastes like this they become exponentially more microbe-and-worm-friendly (especially if you use a combination of tactics). As alluded to, some scraps need less optimization than others. eg there is a big difference between putting some rotting lettuce, or a slice of watermelon into a worm bin, and dropping in a whole potato!

And speaking of potatoes…

Starchy wastes – especially ones high in salt – are a lot less ideal, but it is still possible to process them (in moderation) in a vermicomposting system. The best approach is to chop them up really well and mix them with the variety of other optimized wastes.

Anyway – I hope this helps, Sherman!

Previous Post

Adding Composting Worms to a “Back to Eden” Garden?

Next Post

How Do You Know What’s Worm Castings and What’s Bedding?


  1. Thanks but one thing that concerns me is what causes food wastes to become foul and release poison gases?

    • Steve
    • October 26, 2015

    Optimizing food waste (since that is often a primary food source for aspiring worm farmers) cannot be stressed enough. I initially struggled a bit by not using enough carbons to buffer the food. My first attempt was ALL food waste. Overheating and rancid odors from anaerobic activity marked that learning experience, along with killing off my first batch of worms. An abundance of all-important carbons (like shredded cardboard) will make an oxygen-rich environment, more favorable for the aerobic microbes and the worms.

    • Bentley
    • October 26, 2015

    Hi Sherman,
    Likely the most worrisome gas is ammonia, and it is released when there is excess nitrogen (i.e. when the C:N gets too low) AND when pH gets too high.
    The key is to make sure you are including plenty of bedding materials (as Steve mentions in his comment), and are providing plenty of air flow. You more than likely won’t need to worry about the pH getting too high (often on the acidic side), but be a bit careful with alkaline materials like calcium carbonate.

    • Judy Rhodes
    • September 6, 2016

    How often should I add additional bedding, such as peat moss, dried grass, leaves. Should they be mixed together and added or added separetly?
    Thanks for the help.

    • Steve Bichlmeier
    • September 6, 2016

    Judy, you should add carbons with every feeding. You can layer them just below the food waste you are adding OR mix carbons with the food waste. Personally I prefer mixing food waste and bedding together, plus having a generous layer of bedding on the surface. The dried grass and leaves will soak up excess moisture. My favorite buffer, shredded cardboard,will provide a time-release food too and more airflow than leaves, since they have a tendency to mat together. I’m hesitant about using peat moss because I understand it contributes to the environment’s acidity. We want a more neutral pH for optimum worm activity.

Leave a Reply

Your email address will not be published. Required fields are marked *

Help ‘Spread the Worm’ and Earn!

* Get My Free Worm Business Starter Pack *

Password Reset
Please enter your e-mail address. You will receive a new password via e-mail.