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Common Pillbug (Armadillidium vulgare)


Detailing the physical features, habits, territorial reach and other identifying qualities of the Common Pillbug.

 Updated: 10/24/2018; Authored By Staff Writer; Content ¬©www.InsectIdentification.org




The Common Pillbug is a harmless and delightful way to introduce children to the world of insects, and though it goes by many different names, 'insect' isn't one of them.



Common Pillbug Videos



Pillbugs running as if their lives depended on it

With a plated armor similar to armadillos, it is no mystery how the Genus name for this creature was determined. The Common Pillbug has a different common name in various regions of North America. In the West, they are called Sowbugs (though true Sowbugs are actually in a different genus and do not roll up like Pillbugs). In the Midwest, they are Roly-Polies. In the East, they are known as Wood Lice (not to be confused with the smaller insect known to infest human hair). Oddly enough, Common Pillbugs are not actually insects; they are isopods, making them close relatives to ocean creatures like crabs and other crustaceans.

Pillbugs do not bite and cannot sting. They are slow movers, making it easy to catch and observe them up close. Regardless of what you call them, they are fun to play with. When threatened or disturbed, they roll up into a tight ball, allowing their armor to protect their soft underbelly, head, and many legs. A gentle touch is enough to elicit this response. Pillbugs will remain in that defensive position until the threat is believed to have faded. They are patient. Their time in that defensive, balled-up posture often outlasts even the interest of children.

Pillbugs are considered primitive creatures, but they have an important role in the soil ecosystem. They are an abundant food source for insects and arachnids. Their own diet of rotting organic material like leaves and wood means they help cycle nutrients through the food web. They are easily found wandering under rocks, wood piles, fallen trees and other moist places where decomposition is likely taking place.




Taxonomic Hierarchy
Kingdom: Animalia
  Phylum: Subphylum Crustacea
    Class: Malacostraca
      Order: Isopoda
        Family: Armadillidiidae
          Genus: Armadillidium
            Species: vulgare
Identifying Information
Scientific Name: Armadillidium vulgare
Other Name(s): Sowbug, Wood Louse, Roly-Poly
Category: Isopod
Size (Adult; Length): 4mm to 18mm (0.16in to 0.70in)
Colorwheel Graphic Colors: gray, black, yellow
Descriptors: shell, harmless, round, legs, ball, roll, plates, segments, armor, armor
Territorial Map
Alaska  
Hawaii  
Prince Edward Is.  
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Territorial Reach (A-to-Z)
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
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Alberta
British Columbia
Manitoba
New Brunswick
Newfoundland and Labrador
Nova Scotia
Ontario
Prince Edward Island
Quebec
Saskatchewan
Mexican National Flag Graphic
Mexico
Note: An insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above as they are driven by environmental factors (such as climate change), available food supplies and mating patterns. Grayed-out selections indicate that the subject in question has not been reported in that particular territory. U.S. states and Canadian provinces / territories are clickable to their respective bug listings.