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Can Red Wigglers Eat Mold and Rotten Food?

Can Red Wigglers Eat Mold and Rotten Food?

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Paul Brown

Sometimes it feels like worms will feast on just about anything you toss into your worm bin. Moldy veggies? You bet. Fruits that are near the end of their life expectancy? Sure. But, does it hurt them to consume something that’s gone moldy or even rotten?

Can red Wigglers eat mold and rotten food? Red wigglers can eat mold, and rotten food, but not overly rotten. The longer the food sits, the less value it will be to the worms. Both moldy and rotting compost can be digested and will not hurt the worms to eat.

Whether or not they will eat it is a different story altogether. Typically, red wigglers are not turned off by moldy food and will eat it anyway. But rotten food is often left to… well, rot. Keep reading for more on what kinds of moldy or rotten food you can feed to your worms, and how to tell if what you’re feeding them is pleasing their little worm taste buds.

Red Wigglers and Mold

Red wigglers don’t have tongues, and without tongues, they don’t taste the food in the same way that we do. They have tiny little sensors inside of their mouths that guide them to the best food available. And if you’re lucky, that worm’s eating will propel it right through your compost pile.

Why are Red Wigglers Okay with Mold?

Most worms, red wigglers included, prefer to have their food a little more on the “decaying” side. So, a little old and moldy isn’t necessarily a deal-breaker. In fact, they might actually prefer to eat molded things first.

Generally, the purpose of using worms, particularly red wigglers, in compost piles is to produce a natural fertilizer, right? Mold is a natural event that occurs in the breakdown of our food, so it’s just something that happens. But to red wigglers, it’s nature’s way of telling the worms that the food is ready to eat.

What Kind Of Molded Food Is Okay For Red Wigglers?

We’ve established that mold is safe for red wigglers, and in some cases, even preferred. But that doesn’t mean you can toss any moldy and crusty waste onto the compost pile. The worms won’t eat all of it. To make matters worse, putting the wrong rotting food items in your worm bin can also lead to other issues (source). Here’s a list of a few things that red wigglers can and usually will eat when they’re molded:

  • Raw fruits & veggies (avoid citrus)
  • cardboard (shredded or cut small)
  • Shredded paper
  • Starches (potatoes, bread, etc.) but in moderation

Red Wigglers and Rotten Food

Although rotten food isn’t a whole lot different than molding food, it’s worth noting. Rotten food is the same moldy food, only it’s crossed over the line in some cases. If food is completely rotten, the worms might not eat it.

Why Rotten Food Will Go Uneaten

As previously mentioned, red wigglers are led to their next meal by the tiny sensory cells in their mouths. If something is rotten, that means it’s already passed the threshold of being a source of nutrition and is beyond human consumption. Generally speaking, these foods have lost most of their nutrients and life-sustaining benefits.

If something is beyond moldy and already rotting, it’s more than likely that worms won’t seek out that food. The red wigglers will bypass this snack and let the sensory cells lead them to something more delicious and nutritious.

What Happens to Red Wigglers if They Eat Rotten Food

When food starts to rot, it’s losing oxygen. This means it’s “anaerobic.” Food that’s completely rotten will have zero oxygen, making it unhealthy and dangerous for the worms. Worms breathe through their skin, so eating too much rotten food or even filling your bin with rotten food can actually cause them to suffocate.

More than likely, however, the worms will simply avoid the foods that are not appealing. While they can continue to slowly decompose on their own, this is not beneficial to the bin and is more appropriate for a traditional active composting pile or buried in a dig-and-drop composting approach.

Your worms will thrive when they have food that they can consume and that has the nutrients that they need. Too much rotten food will create an unhealthy environment.

Other Issues with Moldy and Rotten Food in the Worm Bin

We’ve discussed the fact that molded and rotten food can be eaten by red wigglers. But, just like anything in life, everything must be done in moderation. Let’s get a little more into how too much moldy and rotten food can affect your worms, your compost pile, and beyond.

Not being consistent with your red wigglers’ home isn’t just being a poor worm farmer, but it can lead to the bin getting out of balance with pH levels and your worms trying to escape.

Time to Clean the Compost Bin

If you’re adding moldy food to your compost pile and noticing that it’s going un-eaten then clearly, it’s not appealing to your worm palettes. If they’re not eating, they’re not actively composting the food, which is an issue. While a healthy worm bin rarely attracts pests, excessive food items can lead to rodent issues, among other problems.

Wasted food that your worms are avoiding is going to just sit in the compost pile and eventually go from moldy to rotten – and then to really rotten. Then you’ll have a real mess on your hands. While it’s usually perfectly fine to compost rotting fruits and veggies in a traditional compost pile, adding the wrong food items to a worm bin in excess only leads to avoidable issues. And trust me, cleaning the worm bin isn’t exactly a fun task.

But, if you reach this point, watch this short video on how to clean out your vermicompost bin. This will help you make the process as quick and painless as possible, for you and your worms.

Quick Steps To Clean Out Your Vermicompost Bin

Unpleasant Smell

Not all compost piles are stinky. In fact, if your vermicompost pile is starting to develop a stench, something is wrong. A happy and healthy bunch of red wigglers should smell earthy, just like soil.

It’s not the worms themselves that cause foul smells in a worm bin. It’s usually the result of too much rotting food that’s been getting pushed aside. It’s now made its way to the bottom, where it will stay until you retrieve it.

To fix this, you’ll need to find the root of the problem and remove it. Then, you’ll more than likely have to clean the vermicompost bin out. Also, take note of any other food items that you’ve placed in there that the worms were ignoring and note that for future reference. In general, it’s best to avoid pet waste, citrus, meat, fish, and dairy (source).

Attracting Other Critters

Vermicomposting can attract critters when too much rotten food is added to an outdoor worm bin.

If your worm bin is outside, excessively rotten and moldy food that goes uneaten will undoubtedly attract an undesirable group of pests. This is completely avoidable but can easily happen if you aren’t being mindful of what you are putting in and monitoring what the worms are and aren’t consuming.

Adding anything and everything to your worm bin, whether it’s already rotten or close to it will inevitably cause your worms to have roommates that might also use them as lunch. Here are a few of the pests that can find their way into an outdoor worm bin if the food selection and volume is not properly maintained:

  • Rodents
  • Cats
  • Dogs
  • Foxes
  • Raccoons
  • Coyotes
  • Badgers
  • Javelina

Aside from the mess they can make, all these animals digging around in your compost pile will cause the pH of the soil to be unbalanced. Some, like rats, are opportunistic feeders and will the worms that they run across in the bin as well.

Of course, you can reduce a large number of these intruders by maintaining your compost bin indoors but managing the food quantity and selection will still be important to prevent odors and smaller pests that can find their way indoors.

Bad for Allergies

Allergy sufferers know that mold is just about the worst thing to hit your nose. An excess of mold in the red wiggler bin isn’t good for your worm family, but it’s especially bad for your own breathing.

If one of the goals for your red wigglers is to produce natural, organic, chemical-free, super strength fertilizer for your plants, and plants are supposed to help with clean air, it seems a little counterproductive to let it all get moldy. And if you are a vegetarian and growing your own food using worm castings, having this as your worms’ food source may not fit those vegan practices.

We know different animals rooting around in the vermicompost can upset the pH of the soil, leading to an unbalancing of the microbiomes and impeding the composting process. Well, rotten food can also upset the balance of the worms’ home. This can lead to a growth of dangerous fungi, which can also cause those allergies to flare up.

Best Practices When Feeding Compost Worms

Sometimes we make things harder than they need to be. Vermicomposting doesn’t need to be difficult. Follow these best practices on what you are adding to your bin to help the ecosystem that your worms live in within balance.

What to feed compost worms and what foods to avoid.


Red wigglers will eat a moderate amount of moldy or rotting food so long as it’s not in excess. Remember that as food decays, it loses its nutritional value and as a result, it will become less attractive to the worms. They prefer slightly decomposed food but it can reach a point where it is no longer offers the nutrients they are craving. This occurs most often due to continuously having more food in the bin than the worms can consume.

The simple truth is, vermicomposting is not difficult and can be an enjoyable way of making good use of kitchen waste to create nutrient-rich soil amendments for your lawn, garden, or flower beds. It’s generally a better fertilizer or soil amendment than manure and is good for the environment. The key is keeping the worm bin in “balance” and that comes down to moderation.

A few occasional moldy foods should be fine but an excess of rotten foods or the wrong types of foods can disrupt the balance of your worm bin. If you see your worms trying to escape their bin, there is likely something out of balance. Be sure to read, Why Are My Composting Worms Trying To Escape?