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Pillbugs and Sowbugs

Pillbugs and Sowbugs

Order Isopoda

Crustaceanalso: Pillbug, Sowbug, Roly-poly, Woodlouse

Small, gray, armored soil crawlers, the familiar roly-polies, that are crustaceans rather than insects and live by recycling decaying plant matter. They are mostly beneficial decomposers, but in damp, mulch-rich gardens they sometimes nibble seedlings, tender roots, and ripening fruit and vegetables resting on the soil.

🔎 How to spot it

Both are gray, oval, segmented, and up to about half an inch, with seven pairs of legs and a hard, armored back. Pillbugs roll into a tight ball when disturbed, the classic roly-poly, while sowbugs cannot roll and have two small tail-like appendages. Look for them by day clustered under boards, pots, mulch, and debris in cool, damp spots, coming out at night to feed.

🥀 Damage it causes

Pillbugs and sowbugs feed mainly on decaying organic matter and are valuable decomposers, so they usually do no harm. When numerous in damp conditions, though, they can chew on seedlings and new roots and gnaw holes in strawberries, tomatoes, and other fruit or vegetables lying on the soil, often enlarging damage that slugs or rot started.

🛡️ Prevent it

Reduce the damp and decaying matter they thrive in: pull mulch, compost, and debris back from the base of plants, water early in the day so the surface dries by evening, and water less often where practical. Keep ripening fruit such as strawberries and tomatoes up off the soil with mulch, supports, or cages so the crawlers cannot reach them.

🧯 If it is already here

Rarely is any treatment needed, since they are mostly helpful. Where they damage seedlings or fruit, remove their daytime shelter, boards, debris, and excess mulch near plants, and trap them under a hollowed melon rind or rolled damp newspaper, then discard the catch. Drying out the surface and keeping fruit off the ground usually solves the problem without pesticides.

💡 Good to know

It helps to remember pillbugs and sowbugs are crustaceans, cousins of shrimp and crabs, not insects, and are mostly beneficial recyclers of organic matter, so they are worth tolerating except when they turn to seedlings or fruit. Damage is almost always a sign of too much moisture and decaying debris, so drying things out is the real fix.

🌱 Plants it attacks

714 plants in the library can be attacked by this pest

Acorn SquashAdirondack Blue PotatoAdzuki BeanAfrican Blue BasilAfrican MarigoldAgapanthusAgeratumAgrimonyAji Amarillo Pepper🍓Albion StrawberryAlice du Pont Mandevilla🥔All Blue PotatoAlmondAloe VeraAmbrosia CornAmerican BasswoodAmerican Beauty Dragon FruitAmerican BeechAmerican PersimmonAmethyst Falls WisteriaAmish Paste TomatoAnaheim PepperAnemoneAngelique TulipAngeloniaAniseAnise HyssopAnjou PearAnnabelle Smooth HydrangeaAnnual VincaApeldoorn TulipApple MintApril Tryst CamelliaArbequina OliveArizona Sun Blanket FlowerArkin CarambolaArmenian CucumberAroniaArp RosemaryArugulaAshwagandhaAsian PearAsian PersimmonAtemoyaAtlantic Giant Pumpkin🥕Atomic Red CarrotAucubaAugust Beauty GardeniaAunt Molly's Ground CherryAutumn Joy SedumAvocadoBachelor's ButtonBalsam FirBalsam PoplarBanana PepperBarbara Karst BougainvilleaBartlett PearBay LaurelBayberryBeach PlumBeauregard Sweet PotatoBecky Shasta DaisyBee Balm🍅Beefmaster TomatoBenarys Giant ZinniaBengal Tiger CannaBetter Boy Tomato🥬Bibb Lettuce🍅Big Beef TomatoBig Boy TomatoBilberryBing CherryBitter MelonBlack BeanBlack Beauty EggplantBlack Beauty ZucchiniBlack Beluga LentilBlack Cherry TomatoBlack CrowberryBlack Currant🍉Black Diamond WatermelonBlack Kabouli ChickpeaBlack Krim TomatoBlack RaspberryBlack Sapote🥬Black Seeded Simpson Lettuce🥕Black Spanish RadishBlack Tartarian CherryBlack WalnutBlack-Eyed PeaBlack-eyed Susan VineBlood OrangeBloomsdale SpinachBlue Bird DelphiniumBlue Bird Rose of SharonBlue FescueBlue Lake Green BeanBluecrop BlueberryBocking 14 ComfreyBok Choy

For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.