pillbug - Armadillidium vulgare (2023)

common name: pillbug, roly-poly, woodlouse
scientific name: Armadillidium vulgare (Latreille) (Malacostraca: Isopoda: Armadillidiidae)

Introduction - Distribution - Description - Life Cycle - Host Plants - Management - Selected References

Introduction (Back to Top)

The pillbug, Armadillidium vulgare (Latreille), is an isopod, a type of non-insect arthropod also known as a terrestrial crustacean. It is sometimes called a roly-poly due to its ability to roll into ball when disturbed (Figure 1). This defensive behavior also makes it look like a pill, which is why it is sometimes known as a pillbug. The name woodlouse is used for both pillbugs and sowbugs in Europe and refers to where these arthropods are found, such as under logs. Pillbugs are nocturnal, though they may be found during the day in the soil or under debris. They are mainly beneficial in the garden or landscape, but can become occasional pests if they wander indoors.

pillbug - Armadillidium vulgare (1)

Figure 1. Pillbug, Armadillidium vulgare (Latreille), rolled into a ball. Photograph by James Castner, University of Florida.

The pillbug is often mistakenly referred to as a sowbug, which is the common name used for other species of woodlice in the genera Oniscus and Porcellio. Sowbugs and pillbugs are both isopods, but they differ in that a pillbug can roll into a ball and a sowbug cannot. Sowbugs are more flattened and have appendages extending from the last abdominal segment that prevent them from rolling (Figure 2).

(Video) Armadillidium vulgare Isopod Care Guide

pillbug - Armadillidium vulgare (2)

Figure 2. A sowbug, another non-insect arthropod that is often mistaken for the pillbug, Armadillidium vulgare (Latreille). Photograph by James Castner, University of Florida.

Distribution (Back to Top)

Pillbugs were introduced from Europe and are found throughout the world as a cosmopolitan species.

Description (Back to Top)

Pillbugs are nocturnal isopods. During the day they can be found in dark, humid places such as under fallen leaves, rocks, or logs. They are terrestrial crustaceans that live their entire lives on land. Pillbugs feed mainly on decaying plant leaves and other decomposing materials.

(Video) Armadillidium Vulgare - Breeding Enclosure Setup (Common Pilbugs)

Life Cycle (Back to Top)

Eggs: The eggs are carried in a marsupium (brood pouch) on the ventral (underside) surface of the female and can reach a diameter of 0.7 mm. Eggs hatch after three to four weeks. Females may produce one to three broods every year and each brood is composed of 100 to 200 eggs.

Young: After hatching, the young may stay in the pouch on their mother’s underside for an additional one to two weeks and grow to 2 mm in length before venturing off on their own. While in the marsupium, both the eggs and the young survive on nutrients received through marsupial fluid (Capinera 2001).

pillbug - Armadillidium vulgare (3)

Figure 3. Pillbug, Armadillidium vulgare (Latreille), adult and young. Photograph by Lyle J. Buss, University of Florida.

(Video) How to care for Armadillidium vulgare

The young’s first molt occurs within a day after leaving their mother. This first molt allows them to gain the seventh segment of their pereon (the thoracic structure in crustaceans). The second molt takes place two weeks later and allows the seventh pair of legs to generate, originating from the newest thoracic segement. The pillbugs continue to molt every one to two weeks for the next 18 weeks. When molting, the posterior portion of the body sheds first and then the anterior portion sheds around three days later (Capinera 2001).

Adult: The adult ranges in color from gray to brown and reaches 8.5 to 18 mm in length when mature (Capinera 2001). The head has one pair of antennae and a pair of antennules, both used to detect sensory stimuli from the pillbug’s environment. Compound eyes are located on the side of the cephalothorax (the head-like region in isopods composed of the fused head and thoracic segment) (Figure 4). The body of Armadillidium vulgare is made up of a thorax (known as the pereon) with seven segments and an abdomen (the pleon) with uropods (appendages arising from the last segment of the abdomen). Pillbugs have seven pairs of legs, one pair for each segment of the thorax. Males and females can be distinguished by looking at the ventral (underside) plane. Males have copulatory organs on the anterior portion of the thorax and females have a pouch for brooding (the marsupium), if they are pregnant. Adults can live for two to five years.

pillbug - Armadillidium vulgare (4)

Figure 4. Pillbug adults, Armadillidium vulgare (Latreille). Photograph by James Castner, University of Florida.

(Video) Common Pill-Bug (𝘈𝘳𝘮𝘢𝘥𝘪𝘭𝘭𝘪𝘥𝘪𝘶𝘮 𝘷𝘶𝘭𝘨𝘢𝘳𝘦)

Host Plants (Back to Top)

The pillbug’s main habitat is under mulch, fallen leaves, and rocks. Pillbugs are nocturnal and require humid conditions during the day. Pillbugs are generally found in soil with sowbugs, millipedes, and earthworms. Their preferred soil habitat is composed of organic matter and has a neutral to alkaline pH. Pillbugs are least likely to be found in soil that has been tilled, is too wet, or has an acidic pH (Capinera 2001). Pillbugs have also been found feeding on seedlings and some plant roots, leading to occasional minor pest status.

Plants with damage to green leaves by Armadillidium vulgare (Latreille) include Picris echioides and Silybum marianum in the grasslands of California (Paris 1963). Additionally, Armadillidium vulgare (Latreille) was found to cause damage to tomato, radish, lettuce, mustard, pea, and bean crops (Pierce 1907). Armadillidium nasatum has been reported feeding on cucumber plants and fruit (Goats 1985).

Economic Importance and Damage (Back to Top)

A study was conducted on the effects of the detritivorous behavior (consumption of dead plant material) of the pillbug in the hydric hardwood forest of central Florida. The pillbugs’ foraging had a positive impact on the ecosystem, shown by increased mineral layer nutrients (nitrogen, phosphorous, and potassium), increased pH, and higher amounts of carbon eliminated from fallen leaves (Frouz 2008).

Pillbugs may also be found inside of homes, but are not known to cause any damage, only annoy people by being present inside their residences.

(Video) Armadillidium vulgare | Common Pill-bug | Patato bug | woodlouse | Armadillidium isopod | Roly Poly

Management (Back to Top)

Preventing the establishment of pillbugs in unwanted areas is the best management strategy. Pillbugs traveling inside a home can easily be swept up and taken outside. To prevent their re-entry, ensure any floor level cracks and door entries are sealed. Cultural controls for preventing pillbugs from causing damage to seedlings or vegetables and fruit on the soil, may include avoiding overwatering leading to moist soil conditions and removing decaying plant material that may serve as a host area for the isopods. Chemical controls include insecticide bait, dust, granular, and liquid formulations (Capinera 2001).

Selected References (Back to Top)

  • Beck ML, Price JO. 1985. Geneticvariation and differentiation inArmadillidiumvulgare(Isopoda: Oniscoidea). Genetica 66: 169-171.
  • Capinera JL. 2001. Handbook of vegetable pests. Academic Press, San Diego.
  • Frouz J, Lobinske R, Kalcik J, Ali A. 2008. Effects of the exotic crustacean, Armadillidium vulgare (Isopoda), and other macrofauna on organic matter dynamics in soil microcosms in a hardwood forest in central Florida. Florida Entomological Society 91: 328-331.
  • Howard HW. 1980. The distribution at breeding time of the sexes of the woodlouse, Armadillidium vulgare (Latreille, 1802) (Isopoda). Crustaceana 39: 52-58.
  • Koehler PG, Pereira RM, AllenRA. 2012. Pillbugs, sowbugs, centipedes, millipedes and earwigs. UF/IFAS. ENY-221. (26 May 2020).
  • McDaniel EI. 1931. Insect and allied pests of plants grown under glass. Michigan Agricultural Experiment Station Special Bulletin No. 214.
  • McDaniel, E. I. 1924. Greenhouse insects. Michigan Agricultural Experiment Station Special Bulletin 134: 52.
  • University of California Integrated Pest Management Online. 2013. Managing pests in gardens: Fruit: Invertebrates: Sowbugs and pillbugs UC IPM. (26 May 2020).
  • Ziegler A, Suzuki S. 2011. Sperm storage, sperm translocation and genitalia formation in females of the terrestrial isopod Armadillidium vulgare (Crustacea, Peracarida, Isopoda). Arthropod Structure and Development 40: 64-76.


Are pill bugs good for anything? ›

Pill bugs are part of nature's garbage disposal system. Consuming mostly decaying plant matter, and eat rotting vegetation, a pill bug or several are wonderful in a compost pile. In a perfect world, the seven pairs of legs of pill bugs and sow bugs would only touch dead plant parts.

Where are pill bugs found in the US? ›

Pillbugs are relatively long-lived and can survive two or three years. The pillbug is not native to North America and was incidentally introduced from Europe. However, it has spread widely and is a common species within Colorado.

What are pill bugs eaten by? ›

What Eats Pill Bugs? A number of other critters such as birds, toads, spiders, some wasp species, centipedes and millipedes prey upon pill bugs to help support their nutritional needs.

Why do pill bugs roll into a ball? ›

If the pill bug dries out, its gills won't function properly and the pill bug can suffocate. That's why you usually only find them in damp areas, like under a dead log. If they start to overheat and dry out, pill bugs will even roll into a ball to protect the remaining moisture on their gills.

Is it OK to touch pill bugs? ›

Happily, roly-polies are not dangerous. They don't bite, sting, poke or pinch, and instead of running away, they form an easy-to-pick-up, hard ball when you touch them. Roly-polies live interesting lives in yards and gardens near you.

Are pill bugs harmful to humans? ›

Are pill bugs dangerous? Pill bugs are not known to pose any threats to humans. They don't contaminate food or spread diseases. While they are outside, they are pretty much harmless, it's once they get inside that they become a problem.

Do pill bugs bite? ›

Pill bugs do not bite, sting, or carry any harmful diseases. They do not damage household items or deposit eggs indoors. However, they may damage the roots of plants when feeding.

Are pill bugs nasty? ›

Also known as potato bugs or roly-polys, these are the guys that pull themselves into a tight little ball for protection when disturbed. Pill bugs don't bite, sting, carry disease, chew on your house, or do anything else overtly unpleasant, and kids usually love playing with them.

What do Americans call pill bugs? ›

The name is often the most confusing bit. I called them pill bugs as a kid, but others called them potato bugs. In the United States and Canada, you might also call them tomato bugs, sow bugs, wood bugs, armadillo bugs, doodle bugs, roly-polies, carpenters, or boat-builders.

What attracts pill bugs in the house? ›

PIllbugs and sowbugs seek habitats that offer both moisture and decaying plant material. In indoor environments, this means they can be present wherever wood, paper, houseplant debris, or other organic plant material is allowed to lie and absorb moisture.

Why is my house infested with pill bugs? ›

Pill bugs typically enter buildings through door thresholds, especially homes with sliding-glass doors on the ground level. Seeing a pill bug in the home usually means that there is a large population outdoors. Pill bugs do not survive more than a few days indoors without moist conditions and a food supply.

Is a pill bug a roach? ›

A special Thank You to Invertebrate Dude for helping identify this cockroach species! Perisphaerus punctatus most commonly known as the Pill Bug Cockroach (American Cockroach Society), or in Chinese known as the Spotted Ball Cockroach (刻點球蠊).

What do pill bugs hate? ›

Cayenne pepper sauce, chili pepper oil, garlic spray or garden-grade diatomaceous earth can be used to safely battle the pill bug. Garlic spray is made with 1 Tablespoon of crushed garlic per quart of water. Mixing diatomaceous earth with pepper sauce or garlic oil makes a powerful natural pesticide.

What do pill bugs do all day? ›

During the day they can be found in dark, humid places such as under fallen leaves, rocks, or logs. They are terrestrial crustaceans that live their entire lives on land. Pillbugs feed mainly on decaying plant leaves and other decomposing materials.

What is the lifespan of a Rollie Pollie? ›

They look like small roly-poly bugs, and if it is a species that can roll, it can do so at birth. These isopods molt up to a dozen times in their lifetime, and the average lifespan of a roly-poly is between two and five years.

Why are pill bugs active at night? ›

Pill bugs are scavengers that prefer to live in high moisture areas. Since their bodies don't hold water, their bodies are more active at night than during the day. During the day, pill bugs live under wood edging found in landscapes and garden beds, mulch, flowerpots and trashcans. Pill bugs are scavengers.

How long does a pill bug live? ›

Most pill bugs live for up to two years. They are most active at night.

What attracts Rolly Pollies? ›

They both live and breed in moist, decaying organic material and are usually found in areas around the perimeter of houses. A favorite location is under the bottom logs of the woodpile, under potted plants, or in wet mulch.

What kills Rolly Pollies? ›

Apply Insect Killer Granules around foundations, lawns, and landscaped areas to eliminate or repel all kinds of troublesome pests. Scatter Monterey Ant Control, a safe and organic bait containing iron phosphate and spinosad, evenly over the soil around or near problem areas.

Do pill bugs infest homes? ›

The billbug is a common turf pest in most regions of North America. These resilient weevils thrive in a variety of climates. During warm summer months, adults travel over driveways and sidewalks to infest new yards. The insects may gather on home siding, but they rarely come into the house.

What are 3 facts about pill bugs? ›

Fun Fact Friday – Pill bugs
  • Pill bugs are active at night.
  • Pill bugs do not bite or sting people.
  • Pill bugs have seven pair of jointed legs.
  • Pill bugs range in size from 1/4 to 1/2 inch long.
  • When oxygenated, a Pill bug's blood may appear blue.
  • Female Pill bugs carry their eggs around with them in a pouch.
Aug 27, 2015

Do pill bugs carry parasites? ›

Victim: pill bug

(Pill bugs relish bird poop.) Once inside the body of the oblivious roly-poly, the parasite takes over its brain and urges the zombified bug to do crazy things, such as making its whereabouts widely known to its predator, the starling.

Do pill bugs carry germs? ›

The pill bug is often considered a pest when it gains entry into a home. Although they sometimes enter in large numbers, they do not bite, sting, or transmit diseases, nor do they infest food, clothing or wood. They do not spread diseases or contaminate food and are a nuisance simply by their presence.

Do pill bugs attract spiders? ›

The pill bug is harmless to humans and is most often removed from homes because it attracts other dangerous insects, like spiders and scorpions. Though commonly identified by many as insects, pill bugs are actually a terrestrial crustacean.

Do Rolly Pollies turn red when boiled? ›

The recipe is simple, “Collect a quantity of the finest wood-lice to be found (no difficult task, as they swarm under the bark of every rotten tree) and drop them into boiling water which will kill them instantly, but not turn red, as might be expected.

Are Rolly Pollies friendly? ›

Rolly-Pollies are as harmless as can be. They can actually be beneficial to your garden since they will eat decomposed materials from plants and animals, as well as stink bug eggs. Since stink bugs are a major garden and crops pest, having rolly-pollies in your garden is actually a good thing!

Is a pill bug a roly-poly? ›

The roly-poly, or pill bug, is a terrestrial crustacean that looks just like an insect. Oval shaped, with seven sets of legs and a hard outer shell, these creatures are best known for their ability to roll themselves into a perfectly shaped ball when threatened.

What is the biggest pill bug in the world? ›

Bathynomus giganteus, the species upon which the generitype is based, is often considered the largest isopod in the world, though other comparably poorly known species of Bathynomus may reach a similar size (e.g., B. kensleyi).

What country do pill bugs live? ›

Both the common pill bug and the common rough woodlouse are originally from southern Europe and northern Africa.

What is the natural enemy of pill bugs? ›

A pill bug's predators are anything larger: frogs, toads, lizards and small mammals. If you think your seedlings and young plants are under attack by these little creatures, then make sure you water in the morning so the soil surface is dry at night.

Are pill bugs like termites? ›

These bugs are primarily nuisance pests. Unlike termites, carpenter ants, and other home invaders, pill bugs aren't known to cause damage to structures. This means the bugs won't in any way harm your home. But this also doesn't mean you'll want to live with the roly-poly isopods.

What spray kills pill bugs? ›

Pesticide sprays, granules and baits can help control pillbugs outdoors. Permethrin insecticide is more effective than acephate (Orthene) or carbaryl (Sevin) sprays. Other pyrethroid insecticides, such as cyfluthrin, esfenvalerate or lambda-cyhalothrin should also provide control.

Are pill bugs the same as wood lice? ›

The best way to tell the two apart is by counting their legs: woodlice have seven pairs of walking legs, whereas pill millipedes have around 18 pairs. Another difference is that the 'plates' at the rear end of the pill woodlouse are much narrower than those on the rest of the body.

What time of year are pill bugs most active? ›

When are pill bugs active? Pill bugs can be active year-round in mild climates. However, they have a hard time tolerating temperatures over 100 degrees or below about 25 degrees and can die if exposed to these extreme temperatures.

What months do Rollie Pollies come out? ›

They can move quickly and do not require the moisture that the other varieties need. Centipedes are beneficial to the control of other insects, which may be a good reason to keep them around. The most likely time of year to see centipedes in your home is in the spring or fall.

Is a Rollie Pollie a cockroach? ›

They're not bugs at all

They are actually crustaceans, which means they are more closely related to shrimp, crabs and crayfish than they are to the ants and other insects that inhabit the same soil.

Do pill bugs like hot or cold? ›

Typically, pill bugs can tolerate a temperature range of -2 °C and 36 °C4. Thermal preferendum of the species is 22 °C to 23 °C. It is known that these isopods cannot survive in extreme temperatures and prefer cooler, more moderate temperatures.

Do pill bugs prefer wet or dry? ›

Sow bugs and pill bugs are crustaceans, just like shrimps, lobsters and crabs. They breathe with gills, so they need moisture in order to respire. Because of this you should have seen that most of the sow bugs and pill bugs spent more time in the damp rather than the dry soil environment.

Do Pillbugs prefer light or dark? ›

They choose habitats that are dark and damp to stay moist and to avoid dry air or extreme temperatures. They are also nocturnal and huddle with other pillbugs to stay warm.


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