If you’ve ever overturned a rock or log in your garden, you’ve likely seen a group of small, gray, armored creatures curl into little balls. This immediate reaction is what gives them their common name. You might wonder, what do rolly pollies eat? Rolly pollies are detritivores that primarily consume decaying plant material, contributing to soil health. Their diet is a key reason they are considered beneficial visitors to your yard and garden.
These fascinating crustaceans, also known as pill bugs, woodlice, or by their scientific name Armadillidium vulgare, are not insects at all. They are more closely related to shrimp and crabs. Understanding their eating habits helps you appreciate their role in the ecosystem and manage their presence around your home.
What Do Rolly Pollies Eat
At their core, rolly pollies are nature’s recyclers. Their primary mission is to break down dead and decaying organic matter. This process is crucial for nutrient cycling, turning waste into fertile soil. In a natural setting, their menu is quite consistent and revolves around plant-based materials that are already in the process of decomposition.
Here is a detailed list of their preferred foods in the wild:
- Decaying Leaves: This is a staple. Fallen leaves from trees like oak, maple, and birch are a primary food source.
- Rotting Wood: They consume soft, moist, decaying wood, aiding in its breakdown.
- Decomposing Plant Stems: Dead stems and stalks from grasses and flowers are common meals.
- Fallen Fruit: Overripe fruit that has dropped from trees and begun to rot is a tasty treat.
- Vegetable Matter: Any dead plant material, including old roots, becomes food.
- Fungal Growth: They will eat mold, mildew, and other fungi growing on decaying surfaces.
- Animal Dung: Occasionally, they will consume dried manure, which contains undigested plant fibers.
It’s important to note that rolly pollies almost always prefer material that is already soft, moist, and breaking down. They rarely attack healthy, living plants unless their preferred food sources are extremely scarce or the conditions force them indoors. Their mouthparts are designed for scraping and chewing soft matter, not for piercing or cutting live plant tissue.
The Role Of Decomposers In The Ecosystem
Rolly pollies play an indispensable part in a healthy garden ecosystem. As detritivores, they initiate the final stage of the plant life cycle. When they consume decaying matter, they physically break it down into smaller pieces. This material then passes through their digestive systems, where it is further broken down by gut bacteria.
The result is their waste, known as frass. This frass is rich in nutrients like nitrogen, phosphorus, and potassium—the very components of commercial fertilizers. By depositing this frass back into the soil, rolly pollies effectively create and distribute natural, slow-release fertilizer. This process aerates the soil and improves its structure, making it more hospitable for plant roots and microbial life.
What Rolly Pollies Eat In Captivity
Keeping rolly pollies in a terrarium is a common educational project. Providing a proper diet is simple and mirrors their natural one. A well-fed captive colony will thrive, breed, and provide excellent observation opportunities.
Here are the best foods to offer rolly pollies in a habitat:
- Leaf Litter: Collect dried leaves (avoid those from roads or treated yards) and place them in the tank. This serves as both food and bedding.
- Raw Vegetables: Offer small pieces of potato, carrot, squash, or lettuce. These should be replaced every couple of days before they mold excessively.
- Fish Flakes: A tiny sprinkle of high-quality fish flakes provides supplemental protein.
- Eggshells: Crushed, sterilized eggshells offer necessary calcium, which helps them build and maintain their exoskeleton.
- Decaying Wood: Pieces of bark or softwood from untreated trees are excellent.
Avoid feeding them citrus, spicy foods, or anything salty. Always provide a moisture source, like a damp sponge or a corner of wet soil, as they breathe through gills and require humidity. Remove any uneaten fresh food quickly to prevent fruit fly infestations or harmful mold growth.
Setting Up a Rolly Polly Habitat
Creating a home for your pill bugs is straightforward. Use a plastic container or small aquarium with a ventilated lid. Add a deep layer (2-3 inches) of moist, chemical-free potting soil or coconut coir. On top, add a generous layer of leaf litter, small pieces of bark, and maybe a flat stone for them to hide under. Mist the enclosure lightly with water every few days to maintain humidity, but do not make it soggy.
Do Rolly Pollies Eat Live Plants?
This is a common concern for gardeners. Under normal circumstances, healthy rolly pollies do not seek out live, growing plants. Their digestive systems are tailored for decaying cellulose, not the tough fibers and sugars of vibrant vegetation. However, there are exceptions that can lead to them nibbling on your garden plants.
They may sample tender seedlings or very soft fruits like strawberries or tomatoes if:
- The environment is very dry, limiting their usual food sources.
- There is a population boom and excessive competition for decaying matter.
- The plant is already stressed, damaged, or beginning to rot (e.g., a tomato touching wet soil).
- They are trapped in a potted plant with no other food options.
In most cases, damage attributed to rolly pollies is actually caused by other pests like slugs or caterpillars. Pill bugs are often just scavenging the damage after it occurs. To deter them from seedlings, you can use a barrier like diatomaceous earth (when dry) or provide ample alternative food like a pile of decaying leaves away from your garden beds.
What Eats Rolly Pollies?
Rolly pollies are an important link in the food web. Their high calcium content makes them a nutritious snack for many larger animals. By providing food for predators, they support broader biodiversity. Common predators include:
- Spiders
- Centipedes
- Ground beetles
- Frogs and toads
- Small lizards and birds
- Shrews and other small mammals
Their primary defense mechanism—rolling into a tight ball—protects their vulnerable underside from many, but not all, of these threats. Some specialized predators can pry them open or swallow them whole.
Diet Variations and Nutritional Needs
While decaying plants form the bulk of their diet, rolly pollies do require other nutrients for proper growth, molting, and reproduction. Their consumption habits are more nuanced than just eating rotten leaves.
The Importance Of Calcium
Calcium is a critical mineral for rolly pollies. Their iconic armored plates, or exoskeletons, are made of calcium carbonate. They cannot produce this mineral themselves and must obtain it from their diet. Without sufficient calcium, their exoskeletons become weak, making them vulnerable to injury and dehydration.
To get calcium, they will actively seek out and consume sources like:
- Crushed eggshells or snail shells
- Certain types of limestone or chalk
- Calcium-rich soil or sand
- Decaying bones (very occasionally)
This is why you might find them in areas with crushed shell pathways or in soil amended with lime.
Protein Consumption
Protein is another necessary component, especialy for developing young and reproducing females. They typically get protein from the microbial life (bacteria and fungi) growing on the decaying matter they eat. In times of need, they may exhibit scavenging behavior for additional protein sources. This can include:
- Dead insects or other small, deceased animals
- Their own shed exoskeletons after molting
- Feces from plant-eating animals
This occasional protein boost supports their growth and energy needs but does not constitute a primary food group.
Common Habitats and Food Sources
Where you find rolly pollies is directly tied to what they eat. They thrive in locations that provide constant moisture, darkness, and a steady supply of decaying organic material.
Gardens And Compost Piles
Gardens are ideal rolly polly habitats. Compost piles are particularly attractive, offering a warm, humid, and food-rich environment. In a compost bin, they are highly beneficial, accelerating the breakdown of vegetable scraps, leaves, and paper. Their activity helps create richer compost faster. If you find them in your compost, consider them welcome helpers.
Under Rocks, Logs, And Mulch
These areas provide the darkness and moisture they need while being surrounded by their food. The soil underneath is often rich with decaying leaves and wood. Mulch beds, especially those made from wood chips or bark, are prime real estate, offering both shelter and a long-term food source as the mulch decomposes.
Basements And Damp Indoor Areas
Rolly pollies sometimes wander into homes, usualy through cracks in foundations or around door seals. This almost always indicates an outdoor habitat that has become too dry or crowded. Inside, they are scavenging for any organic material, such as:
- Damp paper or cardboard
- Mold growing on walls or floors
- Food particles in forgotten corners
They cannot survive long indoors due to lack of consistent food and humidity. To manage them, reduce outdoor moisture near the foundation, seal entry points, and remove indoor debris they might eat.
Seasonal Dietary Changes
The diet and activity of rolly pollies shift with the seasons, influenced by temperature and moisture availability.
Spring And Summer
These are peak activity seasons. Abundant moisture and warming temperatures accelerate the decay of plant matter, providing a plentiful food supply. They are actively foraging, breeding, and growing. You may see them consuming fresh, soft decaying matter like fallen petals, grass clippings, and early fallen fruit.
Fall
Fall is a critical time for rolly pollies. The sudden abundance of fallen leaves creates a food bonanza. They will feed heavily to build up energy reserves for the colder months. This is when they are most visible and active in the leaf litter.
Winter
In colder climates, rolly pollies become dormant. They burrow deeper into the soil, under logs, or into compost piles to escape freezing temperatures. Their metabolism slows dramatically, and they survive on their stored energy and possibly by very slowly consuming the decaying material immediately around them. They do not eat actively during deep winter dormancy.
Frequently Asked Questions
Are Rolly Pollies Good For My Garden?
Yes, in almost all cases. They are valuable decomposers that improve soil quality. They only become a minor nuisance if their population explodes in a very confined space, like a seedling tray, or if conditions are so dry that they seek moisture in soft fruits.
What Is The Difference Between A Rolly Polly And A Sow Bug?
They are very similar, both being terrestrial crustaceans. The key difference is in defense: rolly pollies (pill bugs) can roll into a complete ball. Sow bugs have two tail-like appendages that prevent them from curling completely and have flatter bodies. Their diets are virtually identical.
How Can I Feed Rolly Pollies To Encourage Them In My Garden?
Simply provide habitat. Leave a section of your garden with leaf litter, a rotting log, or a layer of organic mulch. Avoid using harsh pesticides that can harm them and other beneficial organisms. A moist, undisturbed corner will naturally attract and sustain a healthy population.
Do Rolly Pollies Drink Water?
They do not drink water in the conventional sense. They absorb it through their gills, which require a moist environment to function. This is why they are always found in damp places and will dehydrate quickly in dry, open areas.
Can Rolly Pollies Eat Plastic Or Synthetic Material?
No, they cannot digest plastic or synthetic materials. There is some research into bacteria in their guts that can process heavy metals from soil, but they do not consume man-made waste as food. They might nibble on very thin, decaying paper or cardboard because it is plant-based.