Worms consume a surprisingly wide variety of food, including both plant and animal matter. Although this might suggest that worms are omnivores, they are more accurately described as detritivores—organisms that feed on decaying organic material. This role is essential in any ecosystem, especially in composting environments.
Some worms even consume fungi and soil, making them fungivores and geophagous as well. Dietary preferences vary by worm type. For instance:
Endogeic worms (which live deep underground) consume algae, bacteria, and fungi.
Epigeic worms (which live near the soil surface) feed on nearly any decomposing organic material, such as leaves, grass clippings, fruit and vegetable scraps, and animal waste.
Since epigeic worms are the most commonly used for vermicomposting, they will be your focus when feeding and caring for your worm bin.
What NOT to Feed Your Composting Worms
Although epigeic worms are highly adaptable and can eat a wide variety of materials, certain foods can harm your worm bin. Here’s a list of items to avoid:
Worm Feeding “Do Not Feed” List
Meat and Bones – These decompose slowly, smell bad, and attract pests like rodents and flies. Bones are indigestible for worms.
Salty or Processed Foods – Chips, fries, pickles, and candy are harmful. If you must use them, soak them overnight and discard the salty water.
Pet Waste – Dog and cat feces can contain pathogens and are not considered safe manure for worm composting.
Fresh Green Grass Clippings – Large amounts can cause the worm bin to overheat. Let them dry and compost before adding.
Alcohol – Highly toxic to worms. Overfeeding grains can also ferment, producing alcohol as a byproduct.
Citrus in Excess – Citrus peels contain limonene, a compound toxic to worms in large amounts. Small amounts are fine.
Pressure-Treated Wood – Contains chemicals like cyanide that are extremely toxic to worms.
Why Worms Need Grit (Sand)
In their natural environment, worms ingest soil containing organic material, fungi, bacteria, and mineral particles. These particles move to the worm’s gizzard, where muscular contractions and gritty particles grind food into digestible bits—acting like tiny teeth.
Adding Grit to Your Worm Bin
To help your worms digest efficiently, add some fine sand or soil to the bedding. Most native soils contain grit, but if you’re using pure bedding materials, consider:
Digging a small amount of local soil.
Purchasing fine-grade sand from a garden center.
A little grit goes a long way in supporting digestion and nutrient absorption.
The Worm’s Diet: Food Types You Can Use
There are four main food sources you can use to feed your composting worms:
Kitchen Scraps
Formulated Grain Feed
Animal Manure
Shredded Paper
The food you choose depends on your composting goals—whether for reducing waste, producing worm castings, or raising worms for bait or pet food.
Feeding Worms with Kitchen Scraps
Pros:
Eco-friendly recycling
Produces nutrient-rich compost
Readily available in most homes
Cons:
May attract pests if not managed properly
May not supply enough food if your kitchen produces minimal waste
Kitchen scraps are ideal for hobby worm farmers interested in recycling food waste and producing compost. Avoid adding meat, bones, oily or fried food, and large quantities of citrus.
How to Collect and Store Kitchen Scraps
Use a compost collection container with a lid to reduce odor but ensure airflow. Avoid airtight containers, which can lead to anaerobic bacteria that create alcohol and lactic acid—both harmful to worms.
Drill several small holes in the lid for ventilation or use a purpose-built kitchen compost bin with carbon filters.
How to Prepare Kitchen Scraps
Worms don’t have teeth. They rely on bacteria and fungi to start the decomposition process. Therefore, older, decomposing scraps are actually better than fresh ones.
Fast-decomposing items: Lettuce, apple cores, mushrooms, bread
Slow-decomposing items: Corn husks, broccoli stalks, cabbage leaves
For fibrous materials, chop and freeze them before feeding. This process breaks down the fibers, making decomposition faster.
Feeding Guidelines
A good rule of thumb: feed about one fist-sized portion of scraps per pound of worms. For example, 2 pounds of worms = 2 fist-sized portions.
Feeding Tips:
Use a spoon or gloves for hygiene
Bury scraps completely to prevent pests
Check the feeding spot after 3–4 days
If food is gone, feed again in a different location
Keep a feeding log to track dates, quantities, and food types
If you don’t generate enough scraps, ask friends and family to contribute. Surplus scraps? Freeze them or start an outdoor compost pile.
Feeding Worms with Formulated Grain Feed
Pros:
Complete, balanced nutrition
Easy to measure and track
Accelerates growth and casting production
Cons:
Can be hard to find locally
Overfeeding may cause protein poisoning
What Is Formulated Grain Feed?
Formulated grain feed is typically produced by animal feed companies. Common ingredients include:
Wheat, barley, soybean meal
Fish meal, poultry by-products, alfalfa
Added vitamins and minerals
This feed provides essential nutrients and is favored by professional worm farmers due to its efficiency.
When to Use Grain Feed
Grain feed is excellent if:
Your worm population is large
You don’t produce enough kitchen scraps
You want consistent, high-quality worm castings
You’re composting mostly shredded paper (grain supplements paper’s lack of nutrients)
You can buy it at local feed stores or farm supply centers. Call ahead to confirm availability or request a custom order.
How to Feed Formulated Grain
Use ¼ cup per feeding
Lightly sprinkle over the bedding (like Parmesan on pizza)
Mist lightly with water
Don’t feed again until it’s fully consumed
Track feedings in your worm journal
⚠️ Warning: Avoid Protein Poisoning
Overfeeding grain—especially wheat or corn-based—can turn the bedding acidic. Signs include:
Sour odor
Exploding mite populations
Worms suffering from intestinal rupture
Prevention Tips:
Avoid overfeeding
Add fresh bedding regularly
Use calcium carbonate (2–3 tablespoons) to neutralize acidity and supply essential calcium
Feeding Worms with Animal Manure
Pros
Rich in essential nutrients
Worms thrive on it
Environmentally sustainable
Cons
Can be difficult to source in urban areas
May contain residual medications harmful to worms
Why Animal Manure Is an Ideal Worm Food Source
Animal manure is widely regarded as one of the best food sources for composting worms. Both hobbyists and professional worm farmers frequently use manure to promote healthy worm growth and to produce nutrient-rich worm castings. If your goal is to create high-quality fertilizer for gardening or raise worms for fishing bait, aged animal manure is a top-tier option.
Manure is packed with beneficial microbes and nutrients that worms love to consume. Scientific studies confirm that worms rapidly consume the microbial life in manure, accelerating the composting process and improving nitrogen mineralization—converting ammonium-nitrogen into usable nitrates. The end result? A premium, organic soil amendment gardeners often refer to as “black gold.”
Best Types of Animal Manure for Worm Composting
Not all manure is created equal. Some types are more suitable for worms than others due to nutrient content and safety concerns.
Recommended Manure Types:
Aged Horse Manure – A popular choice among worm farmers. Ensure it has composted for at least 4 weeks to break down any deworming medications. Leaching with water helps remove residual compounds.
Cow and Hog Manure – Widely available and effective. Compost for a minimum of 3 weeks. Remove solids before use.
Rabbit Manure – A “cold” manure that can often be used immediately. If collected from under hutches, leach thoroughly to remove excess urine.
Sheep and Goat Manure – Similar to cow manure; compost for 4 weeks and separate solids before use.
Chicken Manure – Extremely rich in nitrogen and phosphorus. Compost for at least 4 weeks, leach thoroughly, and mix with peat moss or carbon-rich bedding to balance its potency.
🚫 Avoid using manure from meat-eating animals such as dogs, cats, or humans. These can introduce pathogens harmful to worms and humans alike.
Important Considerations Before Using Manure
Before adding manure to your worm bin, ensure it has properly aged—fresh manure is too high in nitrogen and can harm your worms. It should also be thoroughly leached to remove excess urine and medications. Always test a small batch with a handful of worms before large-scale use to confirm their comfort and interest in the material.
How to Source Animal Manure
If you live near a farm or ranch, sourcing manure may be easy. However, even in urban or suburban areas, manure can often be found if you know where to look:
Ask friends or family if they know anyone who keeps livestock.
Use Google Maps or Search terms like “horse manure near me.”
Check Craigslist or Facebook Marketplace for free or low-cost manure offers.
Visit garden centers for pre-packaged, composted manure (check packaging dates to avoid overly aged materials).
When sourcing manure, confirm it has aged properly and isn’t saturated with urine or contaminated with chemicals.
Transporting and Storing Manure
For larger volumes, use a pickup truck or flatbed trailer to transport manure. Avoid enclosed vehicles, as aged manure—while not foul-smelling—contains composting insects you don’t want in your car. Use heavy-duty plastic garbage bags if necessary for safe containment.
How to Use Animal Manure in Worm Bins
Outdoor Setups
If using 100% manure as bedding and food, place your worm habitat in a well-ventilated, well-drained outdoor space. Good drainage helps flush out any residual urine, and ventilation prevents gas buildup.
Indoor Setups
Mix manure with bedding materials such as shredded newspaper, peat moss, or straw. Let it age for another 1–2 weeks. Test by placing the mixture in a sealed container—if it smells earthy, it’s ready. You can also do a worm test by placing a few worms in the material and observing their behavior.
Special Note on Chicken Manure: Due to its high nutrient concentration, always mix chicken manure with a carbon-rich material (like coconut coir or cardboard) and test before wide application.
Manure in Summary
Animal manure is a dual-purpose material—serving as both food and bedding. Worms thrive on the microbial activity within it, but the nutrient value will diminish over time. To keep your worms healthy and productive, add 1–2 inches of aged manure every 2–3 weeks.
Feeding Worms with Paper
Pros
Readily available and affordable
Environmentally sustainable
Great bedding material
Cons
Low in nutrients
Not ideal for fattening worms
Paper products—especially shredded cardboard, newspaper, and office paper—are common materials in worm composting systems. They’re excellent for recycling household waste and producing compost, though they lack the protein and nutrients required for rapid worm growth.
If you’re raising worms for fishing bait, don’t rely on paper alone. Instead, supplement with formulated grain feed or kitchen scraps for a well-balanced worm diet.
Safe and Unsafe Types of Paper for Worms
✅ Preferred Paper Types:
Brown Cardboard & Paper Bags – Shred into ½-inch strips for better surface area.
Newspaper – Breaks down easily and is quickly consumed.
White Office Paper – Slower to decompose but still safe. Shred for best results.
Paper Towels/Napkins – Use only if they haven’t absorbed toxic substances.
⚠️ Cautionary or Unsafe Papers:
Coated/Shiny Paper – Found in magazines, brochures, or receipts; often contains chemicals harmful to worms.
Contaminated Paper – Avoid paper soaked with cleaning chemicals like bleach or window cleaner.
Junk Mail – Shred cautiously; remove plastic windows and coated materials.
Tips for Preparing Paper for Your Worm Bin
Shred everything – Shredding improves decomposition and allows worms to consume it more easily.
Moisten the paper – Dry paper is indigestible. Soak it in water, then wring it out to the damp consistency of a wrung-out sponge.
Avoid oversized pieces – Especially with cardboard; small pieces provide better airflow and microbial activity.
Paper in Summary
Paper is an abundant, free source of bedding and supplemental food for your worms. Brown cardboard and newspaper are best, while white office paper is also acceptable. Avoid using chemically treated or coated papers.
If you’re raising worms for bait or aiming for fast growth, supplement paper with more nutritious options like animal manure, grain feed, or food scraps.
Final Thoughts: Building a Feeding Routine
Feeding compost worms doesn’t have to be complicated. Whether you’re using kitchen scraps or formulated grain, follow these simple tips:
Keep a journal
Monitor worm behavior and food consumption
Avoid harmful items
Rotate feeding spots
Add grit to aid digestion
Ask friends for extra scraps if needed
Freeze surplus scraps when needed
By following these feeding practices, you’ll ensure your worms are healthy, productive, and happy—while turning waste into rich, usable compost.