It seems to happen again and again and again.
Armed with a bin, some bedding, and a shiny new arsenal of composting worms, eager new vermicomposters, our fellow foot soldiers in the War on Waste try to win the war literally overnight.
And they often fail miserably.
Who can blame them? Our intrepid brothers-in-worms have not learned the crucial lesson a vermi-boot camp worth its salt would teach you; that overfeeding is the most common cause of problems in the worm bin.
The grossly over-optimistic rule of thumb that worms can eat 50-100% of their weight in organic waste each day is leading new vermicomposters to certain failure. So it’s high time we explore some common problems in worm bins and reverse engineer how overfeeding can cause each one of them.
Before we begin, it’s worth noting that overfeeding will not necessarily lead to ALL problems below.
But when the first step to solving the problems below is normally to STOP FEEDING, it should serve as a wakeup call that overfeeding is probably the start of most of our problems in the first place.
This article is part of a “Vermicomposting 101” series of posts aimed at helping the beginning vermicomposter. The read other “VC101” articles on how to start a worm bin, how to choose worm food, how to maintain moisture, and the differences between composting and vermicomposting, please visit the Vermicomposting 101 section of this site!“
Common Worm Bin Problems
Overheating
Your worm bin overheating typically indicates you’ve departed the realm of worm composting into simple rotting, which can resemble thermophilic or hot composting. While hot composting is a controlled aerobic process, the enzymatic and bacterial decomposition of excess food waste (especially when piled) releases heat, which can result in a further acceleration of bacterial growth which only makes the problem worse.
If this happens in a large open system like a windrow or a wedge, the worms can escape to cooler areas.
If this happens in a closed system like most home worm bins, then it’s probably lights out for your worms when temps zoom past 100°F.
If you’re able to salvage your bin after an overfeeding, there’s a simple way to prevent a rotting, overheating worm bin. Feed less.
Protein Poisoning (aka Sour Crop)
This is a really interesting – and kind of complicated – way to kill your worms with overfeeding. As protein-rich foods break down, they release acidic compounds. And if these compounds exist in excess and are unbuffered by lime, eggshells or calcium-rich materials in the bin, they will pass through the worm’s crop (which is kind of like a holding tank where food is prepared for digestion downstream) in an acidic state where they will ferment in the gut, offgassing ammonia and alcohol, ultimately rupturing the worm from the inside out.
Sounds pleasant, huh?
As food sources are more acidic and full of protein than bedding materials, the first step is to (surprise!) feed less.
Excess Moisture
Nearly all fruits and vegetables are at least 80% water weight. The more “fun” forms of worm food, like cantaloupe, watermelon, and pumpkin, which worms absolutely destroy, are 90-95% water weight, meaning that the late summer and fall buffets our worms enjoy in the US are a backdoor means of overwatering the bins.
Again, this isn’t a problem for a wedge or windrow where excess moisture can easily drain away to the floor or the earth below, and it’s less likely to be a problem in a breathable bin like the Urban Worm Bag, but if you’re vermicomposting in a plastic system like a single Rubbermaid bin, and you are overfeeding these water-laden foods to your worms, there’s a good chance you’re overwatering them too.
This can can lead to a compacted, anaerobic, and stinky bin.
Solution? Feed less. (You’re probably noticing a trend.)
Fruit Flies and Mites
With the caveat that a healthy worm bin can – and maybe should! – feature critters that aren’t worms, it’s a reality that indoor worm composters will not be pleased to find fruit flies, red mites or other unwelcome guests. To boot, our spouses and roommates may very well veto your vermi-aspirations if dinner gets interrupted by these pests.
I am gone from home quite a bit, meaning I moderately and consciously overfeed my indoor bins, somewhat inviting these problems. My silent partner in the Urban Worm Company, aka my wife, is not silent when fruit flies land on the rim of her wine glass.
I speak from experience.
In short, my indoor worm composting activities are at risk. Don’t let this be you! Again, feed less.
The Bottom Line
The endgame of mismanaging your bins isn’t the risk of overheating, fermentation inside the worms, a wet bin, or fruit flies; it’s the death of your worms or mass exodus and then death of your worms.
Not to minimize it, but this isn’t a huge deal if it happens here and there to just a few new vermicomposters.
But it’s a HUGE obstacle to the widespread adoption of vermicomposting in households if beginners fail by blindly feeding their worms a set ratio of food – which will often be way too optimistic – and then conclude that worm composting is not for them, or that it doesn’t work at all. And it seems to be the most common mistake new vermicomposters make.
So let’s throw out the wild estimates of worms eating 100% of their weight each day. A VERY well-known worm composter in California, who is probably running a highly-optimized system, estimates that his worms only eat 25-33% of their own weight each day.
In fact, let’s eliminate the use of ratios altogether and start from this rule of thumb:
When you underfeed, bad things happen very slowly. When you overfeed, bad things happen very quickly.
Keep in mind that your bedding is decomposing too, albeit much more slowly than food waste will. This means that if you go weeks or maybe even MONTHS without feeding a worm bin, as long as conditions like humidity and temperature are reasonable, you will return to find a worm bin that still has worms in it, doesn’t smell, isn’t too wet, and doesn’t have fruit flies.
Your worms (and maybe your wife?) will be happier for it!
Staying patient and deliberate with your feeding, and observing with your own two eyes when it’s time to feed again will keep you safe from the problems above!
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Yes. I have overfed a little, but my worms are happy and multiplying, however, so have the pill bugs, and at a much faster rate than the worms. I know they are more of a nuisance but I feel like the bin which is a homemade flow through is over run with them. when I gather castings from below, it may have just a few worms included but hundreds of baby pill bugs in only about a quart or so of castings. Should I be concerned? Like separate the worms and start over?
Too DRY!
I have ants that have made a home in my worm bin. I live in a tropical environment so cold isn’t an issue. I moved my worm bins under my orange tree for location convenience. Although they seem to be thriving, there are ants that made a home in the bins. Are the ants harmful to my bin? Thank you!
Hi Lara,
While I am not in a tropical area, the presence of ants actually indicates conditions that may be too dry. I think they would peacefully coexist, but you might end up spritzing the bin daily for a few days and see if that helps.
Cheers!
Steve
Hi Steve,although I have been doing worm farming for over 14 years and one of your subscribers I always look forward to your newsy letters and will find something new to learn.I am a horticulturist by profession and find the two go hand in hand.
MANY THANKS AND WORM REGARDS Esther
Many thanks for the kind words, Esther!
Here’s a way to eliminate almost all your fruit flies; seriously. YOU HAVE TO COOK YOUR BANANA PEELS BEFORE PUTTING THEM IN THE BIN. 100% of bananas have fly larvae on the surface. By cooking banana peels first (I put mine in the toaster oven until their crunchy- easier to break up), I have never had a fruit fly problem in my bins. I’ve had 3; each one has over 10K worms in them. I have also added a copper foil collar at the top of my bin which worms don’t like. They are less likely to migrate out of the bin. It seems to keep everyone playing nicely in the sandbox.
Now THAT is interesting Dawn! If you have just pinpointed a source of fruit flies on a VERY common worm food, then you’d just done everyone a huge service here!
Would freezing banana peels have same effect as cooking?
I love reading your posts because they are informational and written with humorous wit. Great job!
Thanks so much Christina!
Your information is spot on, It’s been very hard to get people to understand “less food is best”. Btw we used closed systems made of wood in various sizes this had made my Worm farming much more successful and less troublesome.
Thanks Debbie! It sounds like you do your vermicomposting in a way similar to Heather Rinaldi of Texas Worm Ranch.
I have a fruit fly infestation in my worm bag. There are whole life cycles in progress–adult flies, larvae, and white little maggots everywhere crawling up the sides and flap of the bag. I know that they are generally harmless, but still they make my skin crawl. On a positive note, my earthworms seem to still be happy. Any thoughts on how I can eliminate the fruit flies (larvae, maggots and all) without endangering my earthworms? Some people have suggested throwing everything out into the backyard but I am loathe to let my worms go.
I have found a solution to the fruit fly problem, and I hope you can help spread this info. The solution to fruit flies is called BTI. There is a good article about it here
https://www.gardensalive.com/product/ybyg-fruit-flies-in-the-worm-bin
It is written by the former editor of Organic magazine, Mike McGrath. He is into vermicomposting and organic gardening and explains how BTI only kills fruit flies and does not hurt any other living creature especially worms.
The stuff I buy is called Summit Responsible Solutions Mosquito Bits. I have been living fruit fly free for over a year after using BTI with healthy worm bins.
Hope this helps
I have one of those worm high rises (vermihut?) . When I lift up a floor to feed a lower floor ther are always lots of worms danglingdown. Does anyone know how to lower the floor and not smush the poor worms? Thank you all, and especially, thank you Steve for running this site.
Eesh, I am not sure. But I guess I am wondering why you would lift up a tray to feed the worms below. The intent of the stackable trays is to promote upwards migration, so you might have the migration of the worms backwards?
Oh!!!! I’m so glad I asked! I put food in all 5 trays. I’ve got LOTS of worms now. Obviously I’m a bit of a newbie! Thank you so much for your response!