Roly Polies in Your Backyard: Common Wild Isopods Across the U.S.

Flip over a rock almost anywhere in America and there's a good chance someone flips over with it.

Roly polies (also called pill bugs, potato bugs, doodle bugs and about a dozen other nicknames) are some of the most familiar little critters in the country. Here's a fun twist: most of the ones you find in your yard aren't originally from here. Many hitched a ride from Europe long ago in soil, plants and ship ballast, and they've been happily munching leaf litter across the U.S. ever since.

Here's how to figure out who's living under your flower pots.

Pill bug or sow bug?

Both are isopods (land crustaceans, not insects!), but they're easy to tell apart:

• Pill bugs roll into a tight ball when bothered. That's the classic roly poly. They have a rounded back end with no obvious "tails."
• Sow bugs can't roll up all the way. They're usually flatter and have two little tail-like points (called uropods) sticking out the back.

Quick test: give it a very gentle nudge. Ball? Pill bug. Flat and running? Sow bug.

Common backyard isopods across the U.S.

Isopods move around with plants and soil, so ranges overlap a lot. These are some of the species people find most often.

Armadillidium vulgare: the common pill bug

The original roly poly. Grey to dark slate, rolls into a perfect ball, and found across much of the country in gardens, lawns and flower beds. If you grew up poking roly polies, it was probably this one.

Armadillidium nasatum: the nosy pill bug

Looks a lot like the common pill bug, but often paler or mottled, and it doesn't always roll into a perfect sphere. It's been reported in many states, especially in the East and Midwest.

Porcellio scaber: the rough woodlouse

A sow bug with a bumpy, rough-looking back, usually grey. Very common in cooler, damper areas like the Pacific Northwest, the Northeast and around foundations and woodpiles almost everywhere.

Porcellio laevis: the smooth woodlouse

A smooth, shiny, fast-moving sow bug, usually grey to brown in the wild. It likes warmer areas and is common in California and across the South.

Oniscus asellus: the common shiny woodlouse

A flat, glossy sow bug with lighter blotches, often under logs and damp wood. You'll see it more in cooler, wetter places like the Northeast and Pacific Northwest.

Trachelipus rathkii: Rathke's woodlouse

A banded, speckled sow bug that's common in parts of the Midwest and Northeast, often in fields, leaf litter and garden edges.

Porcellionides pruinosus: the powdery isopod

Small, quick and dusted with a powdery coating. It loves warmth and is often found in the South, around compost piles and in greenhouses. (Yes, it's the wild version of the Powder Blues and Powder Oranges hobbyists love.)

Sea slaters (Ligia): the beach runners

Live near the coast? Those fast, large "bugs" sprinting across rocks and docks are sea slaters, a group of isopods that live right at the edge of the ocean, on the Pacific, Atlantic and Gulf coasts.

Can I keep the roly polies from my yard?

For a short backyard science project, sure, as long as they go back exactly where you found them. For a long-term pet colony, we recommend captive-bred isopods instead:

• Wild isopods can bring hitchhikers like mites, parasites and pests into your enclosure.
• You don't know what you're getting: mixed species, unknown age and unknown health.
• Moving isopods and releasing pet isopods can be regulated. Never release pet isopods outdoors, and never move wild isopods to a new area. Our transport, release and disposal guide explains why.

Captive-bred isopods give you healthy, known animals, plus colors and patterns you'll never find under a garden rock.

Backyard roly poly FAQ

Are roly polies bugs?

Nope! They're crustaceans, more closely related to shrimp and crabs than to insects. That's why they need moisture: they breathe with gill-like structures. Read more in What Is a Roly Poly?

Are roly polies harmful?

No. They don't bite, sting or carry diseases that affect people. In the garden they mostly eat dead and decaying plant matter, which makes them part of nature's clean-up crew.

Why are there roly polies in my house?

They wander in looking for moisture. A few near doors, basements or bathrooms usually means a damp spot nearby. They dry out quickly indoors and don't infest homes.

What do roly polies eat?

Mostly decaying leaves and wood, plus a little calcium and protein. See What Do Roly Polies Eat?

How do I start a roly poly colony the right way?

Start with captive-bred isopods and a simple setup. Our roly poly pet guide walks you through it, and you can browse all isopods to pick your first species.

Thanks for rolling with us!