Why Do Red Worms Love Brown Cardboard?

I recently received an interesting question from one of our regular readers, Dave P.
I didn’t actually plan to publish it (and my response) here, but Dave thought it might be valuable to get input from others (i.e. Bentley’s response was pretty lame! haha!). Joking aside, I think Dave is right about this being a good potential topic for discussion. Directly below Dave’s question, I’ve included my initial email response (with some minor edits), followed by some additional thoughts added when I put this blog post together.

Over the last few months two things have contrived to make me
ask “why do worms love plain brown cardboard”?

1. I have two 1M cubed compost bins. I recently emptied (bar a few
worms) one and started a new one. I had it about two feet deep with
fresh garden waste, a few buckets of kitchen waste.

2. I happened to have a few items delivered in plain brown card, as
per Amazon books? Nothing special, just brown card. Soak it in water,
pull it apart and leave it for the worms.

Result? My garden compost is magically turned into fantastic
brown/black ‘fertilizer’!

What is it about cardboard that makes them start chomping? An old
‘yellow pages’ book didn’t go down half so well. Yet there is no sign
of the plain card?

I’m mystified. I can’t see any food value in it? Roughage?

Hi Dave,
GREAT question, and something I myself have certainly wondered about over the years. Something I saw suggested once may hold the key. Some have suggested that it might be the glue used in this material that provides the food value – all those layers get stuck together somehow, and it’s probably somewhat similar to that paste we used to use in pre-school. Pretty innocuous stuff, but likely containing some nutrients (polysaccharides for the microbes? I dunno).
The worms seem to love using it as a habitat as well – worming their way down the channels.

Anyway – I guess I’m really not sure at all – but I do LOVE the stuff! If only it was a lot easier to shred it up!

Additional Thoughts

I managed to track down the source of the “cardboard glue” theory mentioned above. It appeared in a Worm Digest article called “Paper Pulp Alone as Redworm Feedstock?!” (Worm Digest, Iss. #22, p.16). Here is the exact quote:

Though the glues in corrugated cardboard are thought to supply a significant protein source, this has not been substantiated

The article also touches on the fact that high-carbon (and low nitrogen) materials like cardboard can be readily colonized by many species of fungi. Given the fact that most of use (who use cardboard as bedding), are also adding other “food” materials (typically with higher nitrogen content), it becomes a bit easier to see how the worms might find the cardboard as appealing as they do. It soaks up juices from the rotting food waste etc, and undoubtedly develops a pretty substantial microbial population as a result.

Anyway – just my 2 cents (with some assistance from Worm Digest).
Thanks for the cool question, Dave! Hopefully others will add some input as well.

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    • Mike
    • September 15, 2010

    When I first started my worm bin I researched a bit about cardboard and found that the glue is made from cornstarch. Totally organic and should be a source of nutrients.

    • Anna
    • September 15, 2010

    Might cardboard be less treated than newspaper? What accounts for the color difference in the two? Could that be the source of the yumminess inherent to the cardboard?

    • Peter
    • September 15, 2010

    Hello, I’ve read similar things about how the cardboard is stuck together. I also read a bit on not to use shredded cardboard sold for insulation because it’s treated with toxic chemicals (fire retardent I’d guess).

    Also when talking cardboard, it’s the stuff used in carton boxes, or ‘corrugated’ cardboard and not the similar rough stuff found on cereal boxes etc. The glue is to stick the corrugations to each side of the cardboard, not to actually bind the paper particials together. Makes sense to me as the first thing to seperate when wet is the corrugated middle part from the walls, leaves a slimey feel on the fingers also. Also makes me feel that maybe soaking in water before putting into a bin might lose you some of this good glue. I’ll soak it now in the bin.


    Paper/cardboard sludge is comprised of the unusable short fibers dredged from the settling tanks during the paper/cardboard recycling process. This material is saturated with the high N glues used to hold together cardboard corrugations, thus, it is actualy higher in N than is shredded paper or even shredded cardboard alone. The (relatively) high N content coupled with the small particle size of the solid bits in the sludge give ample food and surfaces on which microorganisms can grow, and it is these microorganisms that make the sludge a good feedstock for worms. …

    What most of us use in our home worm bins is simply shredded paper and/or cardboard, which is not soaked in high N glue-filled water and has much larger particle size than does paper/cardboard sludge. Further, many people, when referring to cardboard actually mean paperboard (cereal boxes and sixpack cartons), and paperboard has none of the glues found in corrugated that help to amplify the N necessary to promote the microbial growth that maximizes worm activity.

    Taken from a post below.


    • Peter
    • September 15, 2010

    Ack, had posted to ask this but then got carried away. Has anyone run a bin on cardboard for any amount of time? My first bin is about done and I was thinking of just leaving it as is for the worms to finish as much off as possible while the new bin ages and gets ready (about two weeks). I’ve thrown in some more cardboard in but don’t want the worms to starve or get too stressed.

    Goal is to have all food garbage scraps totally eaten and so only have uneaten cardboard to remove from the compost when I harvest.

    PS. on second reading of the stuff I cut, sounds like the corrugated part is made up of glue (not just to stick on the sides). Or maybe it just depends on how/where it’s made, but either way the glue to stick the three parts together is organic so that will help and will be different from things like cereal boxes when you’re choosing material.

    “The corrugated medium is often 26 lb/1000 sq.ft basis weight in the U.S.; in the UK, a 90-gram per square metre fluting paper is common. At the single-facer, it is heated, moistened, and formed into a fluted pattern on geared wheels. **This is joined to a flat linerboard with a starch based adhesive to form single face board.** At the double-backer, a second flat linerboard is adhered to the other side of the fluted medium to form single wall corrugated board. Linerboards are test liners (recycled paper) or kraft paperboard (of various grades). “

    • John Duffy
    • September 16, 2010

    Shredding cardboard can be a real time consuming, tedious task…I bought a really cheap blade for my bandsaw $10 and I cut the cardboard across the grain into 2″ strips. Then, I enlist my grandkids & neighborhood kids in a little “contest.” (a.k.a the Tom Sawyer method)…First kid to fill a 2 gallon bucket with torn/cut cardboard squares wins a dollar…Then, we all have some ice cream and the get to feed the worms….The kids love feeding the worms and learning about worm composting. I’ve gotten a couple parents involved as well and they are all amazed at how quite their kids are while they’re tearing-up cardboard…(who needs toys?)

    • larry duke
    • September 16, 2010

    The euros i have like cup holders more than horse manure! Go figure.I think it’s possible that it may develop some kind of mold they like that we can’t see readily.Mine don’t seem to like bread mold though.

  1. My worms seem to attack toilet paper tubes and Pizza Hut boxes.

  2. Lots of good answers there. The ones I take to are the nutrients in the
    glue (yes, I do use corrugated card) and the good growth
    potential of card for the real food that worms like.
    If card cup holders and toilet paper tubes work, that would
    favour the ‘bug growth’ potential even more.

    At least we have some answers there.. and more importantly,
    the worms seem to love it and thrive!



    • Brian
    • September 17, 2010

    @Peter Thanks for posting your research! I actually stoped feeding my worms box cardboard because they wouldn’t eat it at the same rate but now I night try again because of the high N content, and now I’ve got a workflow down that lends itself to soaking the cardboard. Thanks again!

    • Peter
    • September 28, 2010

    Hmm, considering we want nitrogen in the cardboard, I know worms like coffee grounds and I want to recycle everything….

    I’m thinking of saving any left over coffee and use it as a soaking agent for any cardboard I’ll add. Caffeine has a good bit of nitrogen in it and as the grounds don’t hurt. I’ll see if it goes any quicker than my regular cardboard additions 🙂

    • Bentley
    • September 28, 2010

    I totally forgot to respond to this one. Thanks everyone for chiming in!

    ANNA – Good questions. My hunch is that, yes, brown cardboard is less treated than some other paper products, but I’m not really sure.
    PETER – Thanks for sharing all that! Interesting stuff! I did try to set up a bin using only cardboard as food but it did not seem to perform all that well. I have yet to hear of someone using solely corrugated cardboard with great success. What I’ve always wondered about with the successful use of paper pulp as a worm food is the water that the pulp is being soaked with. As an example, one of the most successful examples of large scale paper pulp vermicomposting was undertaken by a company called American Resource Recovery (pretty sure they are no longer vermicomposting though) – and I think it was their success with the material that actually led a lot of people to wonder about this issue. I have a video (from Vermico) featuring an interview with this company and the one little detail that stood out for me was the fact that they were soaking the material with water from a local canal. Coming from an aquatic biology background, my big question was “what’s in the water?”
    I can only imagine how many microbes, and how much nitrogen etc would be in a eutrophic canal! Yet nobody seemed to offer this as a possibility.
    BRIAN – I definitely wouldn’t go so far as to say that cardboard has a “high N” content, or even that it’s necessarily a good source of nitrogen. If it was, I guarantee that it would decompose much more quickly (since the C:N ratio would be a fair bit lower). As far as cardboard goes, it’s probably a decent source of N though and (as mentioned) when it soaks up liquid from other decomposing waste materials it can definitely become a lot more nutritious.

    • larry duke
    • September 28, 2010

    Bentley,you had to tell us about canal water!:-)
    I started leaving my boxes exposed in a pile outside.I figure it may simulate something like leaf mold.Haven’t had termites move in yet.But they will! But i wait until it rains real good.Then tear up the cardboard easily.Rain water is supposedly perfect ph balanced.But it may wash away some glue that the worms like in the cardboard.
    Hmmmm? That ground disposer cardboard juice may be a magic sauce?????

  3. Hello fellow vermiculturests
    I may have an answer for this mystery question, but the knowledge originates from another discipline. I was a guitarmaker for 27 years, so I know a thing or two about glues[tried them all!] have you ever heard of “hide glue”? Prior to the invention of polyvinyl glues [white glues], resorcinols, epoxies, and aliphatic resin [yellow carpenter types] the ONLY glue was hide glues derived from large beasties, rabbits or fish. Hide glues come in pelletized form, are soaked in water–then heated gently prior to use. Hence the term “glue pot”. Hide glues are water soluable and are the only glue used to put together good quality violins. That is because violins are designed to be taken apart for repairs. Hide glues are used extensively still in industry, paper products, book binding, garnet sandpapaer etc. My best guess is that is what is used for the binder in cardboard.
    Apologies to all of you vegetarians [I used to do that too!]

  4. I thought I wasn’t the only one curious about this subject!!!
    Marc, I think you may have hit upon something there. I do remember my
    dad using the glue pot (odd smell). Not sure what, but I’d
    suggest there are some sort of nutrients in that gloop.

    Now do we have a cardboard box manufacturer on the list,
    to find out if boxes are glued with hide glue!
    Wouldn’t surprise me, such a varied audience out there.

    Thanks Marc.


  5. It would not surprise me if worms liked to eat the microbes that feed on hide glue. I know that mold will eventually consume it. Old furniture that has been kept in a damp place can simply fall apart. it is also the preffered glue for veneer work because it has a controllable stickiness. For more info try THARCO manufacturing. [boxes]

    • February 27, 2011


    • Si
    • June 10, 2011

    Hi…I am a complete newbie to worm farming, and have just started my own bins with my daughter, I am using manure and kitchen vegetable waste, with a shredded paper bedding, I haven’t seen anything going on in the bin so far and it has been 3 weeks all ready, within the 3 weeks I have noticed a big ant problem, these little buggers were attacking the worms, cutting them part and taking them away in section’s, I got worried and read about coffee grounds and moister to get rid of them, unfortunately I live in Thailand and it gets real hot, and I am finding myself watering regularly, to prevent dry up, so I covered the top of my bin with damp corrugated cardboard, since, my worms have taken up living in the corrugated sections by the hand full, I don’t remember starting with that many worms! So I must be doing something right?
    From now on I am going for corrugated bedding! Great stuff! Doe’s this matter at the moment, having them on top, surly they will eat there way back down?
    PS: Great website, I have read a lot, and thanks to all for the great info guys!

  6. @Si, IMHO it is very important to cover the top of the worm bin, mainly
    to stop evaporation. I use an old carpet (not foam backed) which works
    We’re told not to let the worms dry out, hence it is important to ‘water’
    regularly if it hasn’t rained.


  7. Whoops! I just lost all the worms in 3 bins. Those little plastic tray type. The hardware cloth on the bottom was not letting the liquid through–and the whole bins went anaerobic. I will not use the cloth anymore. I have never been wild about using the worm leachate that drips out of the bottom anyway because its usually anaerobicesque. I still have other bins with worms in them.
    In response to the previous comment, my bins were too wet [like mud]–and I think I put too much ‘experimental’ stuff in there–like coffee grounds, orange peels etc. This is really embarrasing because I wrote a book with a big chapter on vermiculture. I guess I am not such an expert after all!

    • Larry D.
    • June 18, 2011

    Marc,don’t worry too much about it.At least you know enough to have more than one batch of worms! Some folks can baby them and kill them all.Sometimes what you think is abuse to worms,turns out to be a new way to multiply them,make them bigger,etc.Just write more than one chapter on vermiculture next time.It takes a big book to cover what Bentley calls “Crazy worm antics!”And a lot of this stuff hasn’t ever been tried.I got some odd experiments coming up that may re write the book on them.Then i’ll have to do it over,because i’ll find out i was wrong! If it was easy,you wouldn’t find worms on free cycle! But it is fun re writing books anyway! Just use”In my opinion!” Or “It worked for me anyway!”It works for me.LOL!

    • Adam
    • May 23, 2012

    I read through most of the comments on this page, but have an additional question: is the glue used to seal cereal boxes and other boxes like Mac and cheese (pretty much all food packaging) non-toxic? When I’m shredding these cartons for the worms, I usually cut off all of the glue before shredding it. Would love it of I no longer had to do this.

  8. Adam I can’t tell you if it’s non-toxic but some of it will not breakdown. I used to wonder what the odd shaped pieces of plastic were that showed up in my vermicompost. It took me a while to figure out it was the glue that was left after the cardboard box had biodegraded.

    • Adam
    • May 23, 2012

    Thanks Mike. I’ll probably just continue playing it safe by cutting all of that glue off. Tedious task, but got to take care of all my little guys.

    • Allan
    • June 21, 2013

    Just picked up a little worm farm, I am a nubie to . Very interesting reading . Tks guys and girls

    • ClaudeA
    • September 16, 2013

    For a number of years when I lived near Hershey, PA, I worked at an now defunct Agway farm coop distribution center. They discarded over a ton of corrugated cardboard away each week.

    On the little country place we lived on I thought to start a worm farm, and hauled many tons of that cardboard to the back of the property. The worms of every kind loved it, and made awesome garden soil for the rest of the years we lived there.

    When we moved I took a galvanized bushel bucket of a gray-colored worm variety along. I put Fall leaves and partly decomposed wood chips in the bucket, thinking that would hold them over. In the nine days’ move to Oregon they worms consumed the entire bushel of material and died out!

    Since they were so voracious eaters I have tried to find what species they are to set up a colony for vermiculture soil production. If anyone reading this has a clue – PLEASE share it!

    I have checked the “Notify Me” box to follow this thread.
    Description of the worms – Light gray and extremely lively. I tried some on a fish hook, but their skin is VERY tough. They were about 2-1/2 to 3-1/2 inches long, max. I did not see them mating, nor did I see their cocoon, so I don’t know the color or size.

    One thing I learned back then in the early 70’s was that corrugated cardboard is glued with food animal packing plant wastes, such as hides, gut and hoof. These are excellent soil amendments, and earth worm feed stock. I presently produce organic soils with garden, kitchen and other organic materials, and quite a bit of corrugated cardboard. I have noticed that I do not need to supply any nitrogen for the high heat necessary for a good composting and the only thing I can figure is the glue in the cardboard. The pile is constantly above 140 degrees F, so the Nitrogen is adequate. About 1/3rd of the source material is corrugated cardboard.

    • Mat
    • February 23, 2015

    I have given my worms the biggest variety of food and bedding material possible over the years and from my observations cardboard is their preferred food. They eat a few types, but these days I use the type of cardboard that eggs come in – grey, fibrous and typically molded. They go mad for it. Not sure if it contains glues – doubt it. Makes me wonder if the glue hypothesis answers the question. It is quite likely that variety of foods is the key for good health and everything does eventually get eaten that is added to the bin, but I do notice a real preference for gray cardboard.

  9. I have used cardboard as the only food souce for feeding my worms in the past. The challenge I had was breaking the cardboard down into small size to feed them with. I found that if I could reduce the size small enough they would eat it very fast. I developed a shredder / grinder that would reduce cardboard to 1/4″ down to dust. This got the worms eating quite prolifically. I would get a 2500 lb bale of cardboard from a manufacturing plant in my town, grind it down in about 4 to 5 hours. This would last about a month for my worms in the end. My worm ben was a straw bale building with a floor space of 100 sq ft. I started with only 5000 red wigglers which turned into around 1 million in the end. I had to move so I sold my property and the worm operation to the new tenant’s.

    I am now raising rabbits and will soon add worms. I found that my cardboard grinder makes great nesting material for the rabbits. So I will see how worms do with rabbit manure and ground cardboard in a continuous worm bed.

    See my grinder at https://m.youtube.com/#/watch?v=B9JHbRpwbwQ
    See my rabbit page at http://kferg9804.wix.com/aharabbits

    Mark Ferguson

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