If you’ve ever overturned a rock or log in your garden, you’ve likely seen roly-polys scurrying away. You might wonder what eats roly polys, as these small crustaceans seem like easy prey. Roly-polys, or pill bugs, are consumed by various creatures including spiders, centipedes, and some small birds.
This article provides a detailed look at the natural predators of these common garden inhabitants. Understanding this food web is key for gardeners and nature enthusiasts alike.
It helps explain the balance of your backyard ecosystem. You’ll learn not only who hunts them, but also how roly-polys defend themselves.
What Eats Roly Polys
Roly-polys, scientifically known as Armadillidiidae, are not insects but terrestrial crustaceans. This places them in the same broad category as shrimp and crabs. Their unique biology makes them a food source for a surprisingly wide range of animals.
Their high calcium content, from consuming decaying matter, makes them nutritious. Predators often seek them out for this reason. The following sections break down their predators by category.
Common Insect And Arachnid Predators
The world of small invertebrates is fiercely competitive. Many insects and spiders see roly-polys as a perfect meal. These predators often share the same damp, dark habitats.
Spiders
Several spider species will readily eat roly-polys. Ground-dwelling spiders, like wolf spiders, are particularly adept hunters. They use speed and venom to subdue these crustaceans.
- Wolf Spiders: These agile hunters don’t build webs but chase down prey, including pill bugs.
- Ground Spiders: Families like Gnaphosidae actively forage in leaf litter where roly-polys live.
- Jumping Spiders: Their excellent vision helps them spot and pounce on unsuspecting roly-polys.
Centipedes
Centipedes are voracious nocturnal predators. Their speed and venomous forcipules (modified front legs) make them effective. They often encounter roly-polys under shared shelter.
The common house centipede and larger soil centipedes are key predators. They infiltrate the tight spaces where roly-polys hide. Their venom quickly immobilizes the prey.
Beetles
Many ground beetles are formidable predators. Both adult beetles and their larvae will hunt for roly-polys. They have strong mandibles capable of crushing the pill bug’s armor.
- Ground Beetles (Carabidae): A large family of beetles known for their predatory habits on small soil organisms.
- Rove Beetles: Some larger species will attack and consume pill bugs.
Amphibian And Reptile Predators
Small amphibians and reptiles that forage in moist areas frequently cross paths with roly-polys. These vertebrates add a different level of predation pressure.
Toads and Frogs
These amphibians are opportunistic feeders. They will eat almost any small creature that moves and fits in their mouth. Roly-polys are a common part of their diet in garden environments.
American toads and common frogs are known to consume them. They use their sticky tongues to capture prey. However, the roly-poly’s defensive roll can sometimes make them difficult to swallow.
Small Lizards and Salamanders
Many small lizards, like skinks, forage in the same leaf litter as pill bugs. Salamanders, which require moist environments, also find them while hunting.
These reptiles and amphibians help control roly-poly populations. They are especially prevalent in gardens with good ground cover and moisture.
Bird And Mammal Predators
Larger animals also partake in eating roly-polys, though they are not a primary food source. These predators typically eat them while foraging for other insects.
Small Birds
Many ground-feeding birds will eat roly-polys. Birds like robins, sparrows, and starlings peck through soil and leaf litter. They find the crustaceans while searching for worms and insects.
Chickens and ducks in backyard coops are also very effective at reducing pill bug numbers. They will scratch and peck relentlessly until they find them.
Shrews and Moles
These small mammals are insectivores, meaning their diet consists mainly of insects and other invertebrates. While tunneling, they readily consume any roly-polys they encounter.
- Shrews: Have a high metabolism and need to eat constantly, making them relentless hunters.
- Moles: Their underground tunnels often collapse roly-poly hiding spots, exposing them.
It’s worth noting that some mammals, like possums, might try them but they are not a preferred food.
Other Unusual And Opportunistic Predators
Beyond the usual suspects, some other creatures will eat roly-polys when the chance arises. This includes certain other arthropods and even some plants.
Ants
While not a major predator, some ant species, particularly larger ones, will attack roly-polys. They may overwhelm a pill bug through numbers, especially if it is injured or molting. They then carry pieces back to their colony.
Carnivorous Plants
In unique circumstances, roly-polys can become trapped in carnivorous plants like pitcher plants. If a pill bug falls into the digestive fluid of these plants, it will be consumed. This is more accidental than intentional predation.
The Roly Poly Defense Arsenal
Despite having many predators, roly-polys are far from defenseless. They have evolved several effective strategies to avoid being eaten. Their most famous defense is their ability to conglobate, or roll into a tight ball.
This action protects their soft underside and presents only a hard, armored exterior. It makes them difficult for many predators to grasp or break open. This is why they are often called pill bugs.
Armor And Chemical Defenses
Their exoskeleton is made of calcified plates, providing significant physical protection. For small predators with weak mandibles, this armor can be impenetrable.
Some species can also excrete a foul-tasting substance when threatened. This chemical defense deters predators that rely on taste, like amphibians and reptiles. Not all species have this ability, but it’s a useful tool for those that do.
Behavioral Adaptations
Roly-polys are primarily nocturnal, reducing their exposure to daytime predators like many birds. They spend the day hidden under objects, in soil, or within dense leaf litter.
Their preference for damp, dark environments also keeps them away from predators that prefer drier conditions. When they do venture out, they move quickly to find cover.
Roly Polys in the Food Web and Ecosystem
Roly-polys play a crucial dual role in the ecosystem. They are both decomposers and prey. This makes them a vital link in nutrient cycling and energy transfer.
Role As Decomposers
Their primary ecological function is breaking down decaying organic matter. They consume dead leaves, wood, and other plant material. This helps return valuable nutrients like calcium and nitrogen to the soil.
By doing this, they improve soil health and structure. This benefits plants and the entire garden ecosystem. Their activity is mostly beneficial to human gardens.
Role As Prey
As a food source, they transfer energy from decaying matter (detritus) up the food chain. Predators that eat roly-polys gain the nutrients stored in their bodies. This supports populations of spiders, birds, and amphibians.
A healthy population of roly-polys indicates a functioning, balanced ecosystem. Their presence supports higher levels of biodiversity by feeding various predators.
Managing Roly Polys in Your Garden
While they are beneficial decomposers, roly-polys can sometimes damage young seedlings or soft fruits. Understanding their predators can help you manage their numbers naturally, without resorting to pesticides.
Encouraging Natural Predators
The most effective long-term strategy is to promote a healthy predator population. This creates a natural balance. Here are steps you can take:
- Provide habitat for spiders and beetles by leaving some leaf litter and rocks in garden corners.
- Install a small toad house or create damp, shady spots to attract amphibian predators.
- Add a bird bath or feeder to encourage insectivorous birds to visit your garden regularly.
- Avoid broad-spectrum insecticides, which will kill the predators along with pests.
Creating An Unfavorable Environment
You can also make your garden less inviting to large numbers of roly-polys. This involves altering conditions to be less ideal for them.
- Reduce excess moisture by fixing leaky faucets and improving soil drainage.
- Clear away dense mulch and decaying wood piles from immediate planting areas.
- Use raised beds for vulnerable seedlings, as they are harder for roly-polys to access.
- Water plants in the morning so the soil surface dries by evening, when roly-polys are most active.
Frequently Asked Questions
What Animals Eat Pill Bugs?
Many animals eat pill bugs, including spiders, centipedes, beetles, toads, frogs, small birds, shrews, and some lizards. They are a common part of the diet for small ground-foraging creatures.
Do Birds Eat Roly Polys?
Yes, many small birds do eat roly polys. Ground-feeding birds like robins, blackbirds, and starlings will peck them up while searching for food in soil and leaf litter. Domestic chickens are also very effective at finding and eating them.
Are Roly Polys Good For Anything?
Absolutely. Roly polys are excellent decomposers. They break down dead plant material, returning nutrients to the soil. They also help aerate the soil as they move. In the food web, they serve as an important prey species for many beneficial animals.
What Kills Pill Bugs Naturally?
Their natural predators, as listed above, are the primary natural control. Diatomaceous earth can be used as a physical barrier, as it damages their exoskeletons. Maintaining a dry perimeter around garden beds can also reduce their numbers in planting areas.
Do Roly Polys Have Any Defenses?
Their main defense is rolling into a hard, armored ball that protects their vulnerable underside. Some species can also secrete a foul-tasting liquid. Their nocturnal habits and preference for hidden, damp places also help them avoid predators.