Isopods - The Ultimate Partner for Your Composting Worms?

Vermicomposters - especially new ones - often have tunnel vision. The worms are (understandably) their primary focus - their pride and joy - while other creatures in their worm bins tend to be viewed with suspicion or, at best, mostly ignored.

One such creature is the lowly isopod  - a composting ally that offers a lot more waste processing potential than most people realize!

In this installment of our ongoing critter series we’ll look at:

• How isopods fit into the bigger ‘critter classification’ picture.
• The roles isopods play in natural ecosystems.
• The key requirements isopods need in order to thrive (and why they often don’t in regular worm bins).
• How to harness the waste-processing abilities of isopods in a more intentional way.
• The importance of working with local isopod species, and how to find them.
• A super simple isopod-worm composting system you can set up in 15 minutes or less.

Our hope is that by the end of this article you’ll come to see these curious creatures in a whole new light!

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What Exactly Are ‘Isopods’?

Often thought of as “bugs”, isopods are actually a type of crustacean. In other words, they are much more closely related to lobsters and shrimp than they are to insects. So, it might not be too surprising to learn that more than half of the 10,000+ known isopod species are actually aquatic - most of them living in marine environments.

Fun Fact: the largest isopod in the world is Bathynomus giganteus, a deep sea species that can reach a length of nearly 2 ft and weigh close to 4 lb!

Thankfully, our terrestrial isopod friends are much smaller! 😂

Isopod Classification

Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Isopoda
Suborder: Oniscidea (includes all of the terrestrial isopods)

There are more than 35 families of terrestrial isopods. Some of the more significant ones for our purposes include: Armadillidiidae, Porcellionidae, Oniscidae, and Philosciidae.

NOTE: The sheer number of terrestrial isopod species and their widespread presence in natural environments is one of the significant differences between working with isopods vs composting worms (and one of the key reasons composting with isopods can be easier and less expensive to get started).

Role of Isopods in Natural Ecosystems

Isopods are very important primary decomposers, shredding tough organic matter, such as dead leaves and wood, vastly increasing the surface area for microbial colonization. This in turn helps other organisms, such as earthworms and springtails, to convert these materials into rich humus, and ultimately helps to return vital nutrients to the soil.

Apart from their important role in nutrient-cycling, isopods can also play a valuable role in ecosystem remediation and protection by accumulating metals such as, lead, cadmium and copper - helping to prevent them from leaching into groundwater and making their way further up the food chain. This is a bit of a double-edged sword, however, since contaminated isopods may still be consumed by other organisms such as birds or shrews, potentially leading to hazardous accumulation in these animals, repercussions further up the food chain, and spread of these contaminants to other geographic locations. 

 

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How Do You Actually ‘Compost with Isopods’?

A big part of why isopods aren’t generally considered major composting players - at least not in the same league as composting worms - is likely due to their very specific requirements. These are requirements that often aren’t provided in composting systems, especially not indoor worm composting systems.*

When you do meet these needs - which is surprisingly easy - it’s like a whole new “level” of composting potential opens up!

* NOTE: It’s worth mentioning that you can indeed find a huge abundance of isopods in some composting systems, especially neglected outdoor systems. What’s ironic, though, is that, more often than not, the reasons they are actually thriving are some of the same reasons the system itself isn’t operating at peak efficiency. E.g. systems with too high a proportion of “browns”, and/or ones that are excessively dry (by composting standards) can often have large populations of isopods.

What Isopods Need to Thrive

On the surface, isopods may seem somewhat more “demanding” than composting worms, but meeting their needs is actually quite easy with a little extra focus and effort. Even better, your composting worms can help the isopods in some important ways that wouldn’t happen without their presence.

Key Isopod Requirements:

Excellent airflow - This one helps to explain why isopods often don’t thrive in more typical, enclosed plastic worm bins, yet can seem to thrive in outdoor (especially neglected) systems.

A steady supply of natural “browns” - This is another requirement that can often be in short supply in a more typical worm bin. Dead leaves, in particular, are basically an isopod “superfood”, so we highly recommend stockpiling them if you’re interested in this approach.

A source of calcium - Unlike worms, isopods have an exoskeleton that needs to be maintained (and periodically shed). Calcium is a key nutrient required for this building/maintenance. The good news is that it is very easy to provide it simply by periodically sprinkling in calcium carbonate, calcium-rich rock dusts, ground up egg shells, or even by adding solid chunks of limestone or chalk.

A source of protein - This is another important building block for isopods, and one you will need to be more proactive about than with composting worms - especially once your isopod population gets a lot bigger. One of the perks is that you can actually add some materials you wouldn’t normally add to a worm bin (e.g. meat) - but moderation is still very important!

Dry zones - Yet another requirement that helps to explain why isopods might not be thriving in your enclosed, plastic worm bin, but also one of the reasons combining isopods and composting worms can be such an effective strategy. Dry materials - especially tough “browns” - can take a very long time to break down in composting systems, but with the help of isopods, you can process these wastes in a fraction of the time, and help your microbes and worms in the process.

Damp zones - Terrestrial isopods have specialized breathing organs that require moisture for gas exchange, so conditions that end up too dry can quickly become deadly. The good news is that if you are providing enough moisture for your composting worms, you should have more than enough for your isopods!

Helpful But Not Critical:

Water-rich foods - Fruit and (especially) veggie wastes can offer an easy source of additional nutrition and moisture for isopods in the same way they are helpful for worms, but one major perk in the case of isopods is that they will readily feed on very fresh materials that would last much longer in a regular worm bin (e.g. fresh carrots, cabbage, potato).

Places to hide - In natural settings, isopods are drawn to physical structures that offer protection from the external environment. This is why you often find concentrations of them underneath pieces of wood, rocks and other materials that have been sitting in one spot for an extended period. In an isopod-worm composting system, simply adding some extra structures, like avocado rinds, pieces of bark, or even intact egg carton cardboard, can help.

Why Isopods and Worms Can Work So Well Together

What’s great about the isopod-worm partnership, when both their needs are being met, is that these two organisms can help each other out in some pretty significant ways.

We’ve touched on some of the key talents isopods bring to the table, including:

• Rapidly breaking down tough, natural “browns”.
• Processing wastes in pretty dry conditions.
• Feeding on much fresher wastes than worms.

All of these lead to a more microbially-active environment, and more materials that the worms can readily process.

Worms, on the other hand, can:

• Consume rotten wastes the isopods don't get to (these materials can lead to problems in isopod-only systems).
• Feed directly on isopod feces, reducing the potential for ammonia spikes and other hazards associated with their accumulation.
• Help to ensure that moisture levels in the system are sufficient (apart from the water-rich wastes being added as a food source, the worms themselves are basically little bags of water, and they tend to release some of their water weight as conditions get drier).

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As great as these two organisms can be together, achieving a “perfect” balance can be somewhat challenging. We recommend opting for one of these two strategies (per system), depending on your preferences/goals:

1. Isopod-Centric Approach - In this case you are catering primarily to the needs and talents of the isopods. This can be especially valuable in cases where you are less interested in worm composting and more interested in processing large quantities of resistant “browns” like fall leaves. The end product, while certainly valuable as a form of compost in its own right, can also serve as an amazing “living material” in worm bins (one of the best we’ve worked with so far).
   
   
2. Worm-Centric Approach - As you might guess, this is the approach better suited for avid vermicomposters who want to harness the talents of isopods in a more typical worm composting system. While it can be somewhat more challenging to find your isopod “sweet spot” with this approach, some of the advantages include being able to process resistant materials much more quickly, and potentially producing a higher quality of castings (than strict isopod composting or even regular vermicomposting).

To be clear, isopods and worms are still important in both cases. It’s more a matter of which organism you choose to be the main driving force.

Getting Started With Isopod Composting

One of the unique perks of working with isopods is that they are usually locally available - often in great abundance. So (unlike with composting worms), you shouldn’t even need to purchase your starter supply.

In fact, one of our biggest recommendations for anyone interested in this “isopod composting” idea is to only work with varieties you can find locally. Isopods are not only much more mobile than composting worms, but they also thrive in a much wider range of natural habitats. When you use one of the varieties that are popular in the isopod-keeping hobby - a real ‘thing’, believe it or not 😆 - you risk introducing invasive species into your local ecosystem, unless all of your systems are indoors and the compost is only being used indoors.

Finding Local Isopods

During warmer months of the year it should be relatively easy to track down a good starter supply of local isopods for your first system(s). They can be found under logs, rocks, and other pieces of debris that have been sitting in one spot for an extended period. Initially, we suggest not worrying too much about what specific varieties you are collecting, but the mini-guide below features some of the more common ones you can watch for, including our #1 recommended species.

4 Common Isopod Species Found In Canada

Armadillidium vulgare (Roly-Poly, Basketball Bug) - These are one of the most widespread and abundant isopod species in the world. When most people think of isopods,it’s usually these guys that come to mind. What’s interesting is that most isopod varieties actually can’t roll into a ball the way A. vulgare can (the fancy term for this is “conglobation”, just in case you need a fun fact to share at your next dinner party). The jury is still out as far as using this variety for composting goes - but it does seem to offer a lot of promise - especially in cases where it isn’t competing with other species.

Porcellio scaber (Rough Woodlouse) - This is another incredibly common isopod species, with a range likely similar to A. vulgare. They are easy to tell apart, though, due to their much flatter body, faster movement, dull and rough (not shiny and smooth) appearance, and their inability to roll into a ball. If you are interested in the idea of composting with isopods - and you can find this species in your region - it is definitely the one for you (in our humble opinion). Its breeding and waste-processing abilities are seemingly unmatched!

Oniscus asellus (Skirted Woodlouse, Shiny Woodlouse) - This is another very common variety of isopod, especially in more sheltered, natural settings. They can look like P. scaber to the untrained eye, but tend to be larger (especially in width), and they have much more of a distinct coloration and shine. They aren’t as promising for composting, though, since they prefer cooler temperatures and tend to breed more slowly.

Philoscia muscorum (Common Striped Woodlouse, Fast Woodlouse) - This isopod species has much more of an “insect” look than the other common varieties, and it can also be found in a wider range of habitats. Some of our initial work with P. muscorum suggests that it can do quite well in really damp environments - offering some promise for use in more typical worm bins - but more testing is needed. As the name suggests, this species is also known for its rapid movement. 

 

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Setting Up Your First Isopod-Worm Composting System

We almost never recommend using buckets for worm bins (other than our DIY in-ground bucket system), but one of the easiest ways to start testing the waters with isopod-worm composting is with a basic 5 gallon bucket. It’s a container most people already have (just make sure you are using a food-grade bucket that hasn’t previously contained anything toxic). It’s lightweight and easy to move around, and it hardly takes up any space.

The set-up process for these systems is even easier than for our DIY Worm Bin.

STEP #1 - Line the upper, inner walls (4”-5”) of your container with clear packing tape. This is a precautionary measure intended to help you avoid any issues with isopods climbing out of your system. Just so you know, our recommended variety, Porcellio scaber, cannot climb plastic walls at all, nor can A. vulgare. This is more of a precautionary measure in case you end up with one of the varieties that can climb (the packing tape will be like a vertical ice rink for even the best climbers).

STEP #2 - Create a 3-4” false bottom of coarse, damp cardboard (ideally brown corrugated cardboard or egg carton cardboard) down in the bottom of your container. This is mainly for your worms. As much as isopods love “browns”, these materials usually need to be directly from a natural source or - in the case of paper products - very well-aged.

STEP #3 - Add 2-3” of some form of “living material” (if you want to combine this with adding composting worms, our Living Material Plus is an excellent option), or even an organic potting soil - not regular soil - directly over top.

STEP #4 - Add a modest amount of water-rich food scraps like leafy greens, melon, cucumber - or really anything else you happen to have available. If you have not already added some composting worms with your living material, this is a good time to add them. There is no minimum quantity, but if you are using a bucket or small tote, we suggest adding 50-100 worms. This gives them the opportunity to establish their “perfect” population size for the system. 

STEP #5 - Fill the system up to within 3-4” of the rim with your natural “browns”, along with your starter culture of local isopods. There is nothing better than dead leaves, but any dead plant matter that has been sitting outside for a while can work. 

NOTE: If you are using a powdered calcium source (like our pH Buffer/Grit), you can lightly sprinkle it in at various points during the set-up process. ¼-½ cup for the whole system should be more than enough to get things started. If you prefer a solid calcium source simply add one or two pieces somewhere in your main “browns” zone. As funny as it might sound, our favourite solid option is actually sidewalk chalk. It’s readily available, inexpensive, and offers the advantage of providing you with a visual indicator of how much calcium is available in the system (more challenging to assess with powders).

A Word or Two About Woody Materials

Old wood chips, dead bark, even larger chunks of rotten wood can be very helpful in any type of system containing isopods. 

They provide shelter, help to support excellent airflow, and the isopods will gradually feed on them over time. Just keep in mind that they can take a long time to get fully processed, and they can also take up a lot of room. 

We suggest adding them in moderation, especially in smaller systems. One perk (apart from the ones already mentioned) is that they can get recycled through multiple system cycles, and they’ll only get more valuable over time!

Preparing Natural Materials for Use

When using leaf litter and other “browns” that have been sitting outside for any length of time, there is a good chance there will be a pretty diverse ecosystem of organisms already living in them (i.e. critters that can come along for the ride when you collect the material). This isn’t necessarily a deal-breaker, but if you end up with predators like centipedes and spiders in your system, it may impede early isopod population growth and make working with the system less pleasant. 

If this is a concern, there are a few solid options for helping to reduce the number of hitchhikers (or eliminating them altogether):

1. Solar Baking - Spreading the material out on a dark coloured tarp and letting it sit in the sun for a few days is a simple option that should work fairly well (assuming you have some consistently warm and sunny weather). If you place a sheet of clear plastic over top it should make this method even more effective.
   
   
2. Water Bath - A method less dependent on weather conditions involves submerging your materials in a container of water to dislodge (and potentially drown) any invertebrates living in them. The most effective version involves actually weighing down the materials (i.e. forcing them to stay submerged) and leaving them to sit for a day or two - but even a fairly quick water bath can be surprisingly effective, especially for dislodging, and separating larger invertebrates like centipedes. Just keep in mind that it will also be important to drain excess water from your materials before adding them to your system, since they should be damp, not sopping wet.
   
   
3. Oven Sterilization - This involves baking your “browns” at 200-250 F in your oven for 30-60 minutes. This is likely the most popular choice in the isopod-keeping world - and undoubtedly the most effective approach - but it’s actually our least favourite option, since we prefer to preserve at least some of the original biology in these types of materials. We’re also not so sure your loved ones will be thrilled with the idea of you baking leaves and wood chunks in the oven! 🤣

Some Important Things To Keep In Mind About Composting With Isopods

• Don’t be too lax with the isopod requirements discussed earlier. These can truly mean the difference between total failure and incredible success with these organisms. Excellent airflow and making sure you always have lots of natural “browns” in your system are likely the two most important ones to always remember.
  
  
• Keep in mind that it can take some time for your “isopod engine” to really hit its stride. Early on it might feel like nothing much is happening. One contributing factor is that you’ll likely be starting with a smaller quantity of isopods (than you would be with worms in a regular worm composting system), so having some patience will be an important part of the process. What’s nice is that these systems can be a lot more “set and forget” than regular worm bins - so you may find it easier to focus on other things while your isopod population grows.
  
  
• “Browns” should be your main “food” (especially in isopod-centric systems). As counter-intuitive as it might seem for experienced vermicomposters, a great deal of your system nutrition will actually come from the “browns” that get added. You should think of your water-rich wastes more as a supplement than as a primary food material - at least early on. Once these systems really hit their stride they can actually process a surprisingly large amount of regular food wastes as well - but “browns” remain every bit as important, even then.
  
  
• Isopod population growth can catch you off guard if you aren’t prepared. While it can feel like nothing much is happening with your system early on, it can then suddenly feel like your isopod population has exploded “overnight”. One possible explanation is that isopods don’t lay eggs - they carry their young until they are ready for release - so a lot of females releasing young at the same time ends up feeling a lot different than worms dropping a lot of cocoons! In terms of “preparation”, you can plan for starting up new systems (maybe bigger systems), helping other people who are interested in composting with isopods, or using them as a live food organism. We’ve had good success using isopods as a fish food, but they could likely be a nice treat for chickens and other foul, or reptiles and amphibians if you happen to have them.

 

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Final Thoughts

Many composters are familiar with isopods - some even view them as a helpful player in the composting ecosystem - but it’s safe to say that very few people are harnessing their composting talents in any sort of intentional way!

Anyone who heads down this path can enjoy some unique perks not typically available via more traditional methods - in particular, the ability to process large quantities of resistant “browns” much more quickly.

To be clear, there is much more that could be said about this topic than we’ve shared here - and we do hope to share some related follow-ups in the future - but hopefully we’ve at least provided readers with a starting point for harnessing the power and potential these amazing crustaceans - especially when partnered with composting worms. 

Like any effective composting approach, composting with isopods does require some dedication and focus - but, as we’ve discovered, the results can be more than worth the effort!

Have any questions, comments, or experiences to share related to isopods? Need any assistance with identifying local varieties? As always, don’t hesitate to get in touch. We love hearing from you!

 

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Other Articles You May Be Interested In

An Introduction to Worm Bin (Macro) Invertebrates
Springtails - White Plague or Worm Ally?
The Birds and the Bees of Composting Worms
The Real Dirt on Composting Worms
Fruit Flies & Gnats
What Is “Living Material”?
Bedding - The Most Important Material in Your Worm Bin?
DIY Plastic Worm Composting Bins

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