Are Roly Polys Good For The Garden?

One of the animals we raise at Ficarro Farms is the pill bug, often called a roly poly. If you find them under a pot or a layer of leaves, you may wonder whether to welcome them or worry about your plants. The useful answer is: usually welcome them, but look at what is actually happening in your garden.

What are roly polys doing in the garden?

Pill bugs and sowbugs are terrestrial isopods, not insects. They favor cool, moist shelter and feed mainly on decaying plant material. By chewing leaf litter and other debris into smaller pieces, they take part in decomposition alongside fungi, bacteria, and other soil organisms. That is a good reason to leave an ordinary garden population alone.

Our original post described isopods in terrariums with live plants, where we saw them favor decaying material. That is a useful observation from those setups, but it does not mean living plants are never eaten. If you find damage on tender seedlings, fruit touching damp soil, or succulent parts, check the plants at night. Isopods can sometimes feed on living tissue, particularly where populations are high and decaying food is limited. Seeing one nearby does not prove it caused the damage.

Do isopods make contaminated soil safe?

No. Some studies measure metals taken up by terrestrial isopods, including Porcellio scaber. That makes the animals useful for studying exposure in a particular environment. It does not show that a garden becomes free of heavy metals, that vegetables are protected from contamination, or that an isopod is safe to feed to another animal. Soil safety requires appropriate testing and advice for the specific site; watching roly polys is not a test.

For the same reason, neither an “organic” label nor the fact that an animal was raised in a culture is a laboratory guarantee that it is free of contaminants. If you plan to use isopods as animal food, consider the source and the needs of the animal you are feeding, rather than relying on a blanket purity claim.

So should I remove them?

For a typical garden bed, there is usually no need to remove pill bugs just because you see them under mulch. They are part of the decomposer community. If you see actual feeding damage, first identify the culprit and the conditions that favor it. Keeping ripe fruit off damp ground and adjusting an overly wet, debris-heavy area may help, depending on the problem. The University of California IPM guide has identification and garden-management details.

If your interest is a contained observation colony or a classroom activity, start with our setup and arrival checklist and compare the live isopod listings. Do not release purchased animals into the garden or outdoors. Have a question about your project? Contact us.

Sources: University of California IPM, Pillbugs and Sowbugs (decomposition and occasional crop damage); Udovic and colleagues’ P. scaber bioavailability research (metal uptake as an exposure measure). These sources do not establish contaminant removal or the safety of a particular product.