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Armadillidium vulgare
pillbug


By Courtney Jane Brown

Kingdom: Animalia
Class: Malacostraca
Order: Isopoda
Family: Armadillidiidae
Genus: Armadillidium
Species: Armadillidium vulgare
Members of this Species

Geographic Range

You have probably seen them in your basement or garden, for they live under stones and bark in damp places. While they exist in large numbers here in North America, they also reside in the wettest areas of Germany.

Biogeographic Regions
nearctic (Native ); palearctic (Native )

Habitat

Pill bugs hide in damp places during the day and are active at night. Under moist areas such as bark and stones, they make their burrow (living quarters.) One of the pill bugs' most surprising characteristics is that they have such a wide distribution pattern. "Home" can be a forest, garden, or basement.

Terrestrial Biomes
savanna or grassland ; forest

Physical Description

Their light shell-like crustaceous exterior is usually a drab earthy color. Pill bugs found in North America range from gray to brown. However, those with habitats in Europe have large red dots, which give them protection by conferring a resemblance to black widow spiders. Pill bugs have five abdominal segments which are distinct dorsally. Their first antennae are vestigial.

Reproduction

A. vulgare reproduce on land as opposed to in water. Eggs develop in a brood pouch filled with fluid, from which fully developed young are released. They produce between one and two broods. The number produced depends on the size and condition of the female, who may cease to grow under stress due to excessive hydration, which reduces the chance of a second reproduction. Ironically, when the food supply is short, the offspring grow larger.

Behavior

Pill bugs live in an arrangement where the father reigns supreme. He guards the burrow in which the family lives. The monogamous pair (the mother and father) gather food for the entire family. Then, the entire family cleans the burrow of faecal pellets. Faecal pellets are carried outside the burrow around the entrance. In February the family disbands and the young set out to make new families of their own. However, the juveniles will always stay within 10 to 100m of the family's main burrow.

Food Habits

A. vulgare, like most isopods, are omnivorous. They feed on fungi, live or dead plants and animals. Special treats for pill bugs are monocotyledonous leaves. All isopods increase decomposition by processing leaves through their alimentary canal. It is not uncommon for pill bugs to shift from one type of food to another, for during a drought they turn from being vegetarians into scavengers.

Predation

Known Predators


They are famous for curling up into a tight ball for a defense mechanism. Some may secrete a substance which discourages spiders. The most common defense among all of them is to remain inconspicuous.

Ecosystem Roles

These animals are part of the community of species that break down dead plants and animals.

Ecosystem Impact
biodegradation

Mutualist Species

Economic Importance for Humans: Positive

Pill bugs living in gardens help circulate soil, although they may also eat small plants.

Economic Importance for Humans: Negative

Pillbugs may occasionally eat small plants as they germinate, causing some trouble in gardens.

Conservation Status

IUCN Red List [Link]
No special status

US Federal List [Link]
No special status

CITES [Link]
No special status

State of Michigan List [Link]
No special status

Pill bugs are quite common and have no special conservation status.

Other Comments

They are famous for curling up into a tight ball for a defense mechanism. Some may secrete a substance which discourages spiders. The most common defense among all of them is to remain inconspicuous. They have a life span of up to five years!

For More Information

Find Armadillidium vulgare information at

Contributors

Courtney Jane Brown (author), University of Michigan.

References

Philip, P. 1988. The New Encyclopedia Britanica. Fifteenth Edition. Page 416

Warburg, M. 1993. Evolutionary Biology of Land Isopods. Springer-Verlag, NY. Pages 50-53, 69, 70-70, and 101.

Pearse/Buchsbaum 1987. Living Invertibrates. Blackwell Scientific Publications, Palo Alto, California. Page 514

To cite this page: Brown, C. 1999. "Armadillidium vulgare" (On-line), Animal Diversity Web. Accessed February 12, 2012 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Armadillidium_vulgare.html

Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

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