University of Maryland Extension

Pillbugs and Sowbugs


Key Points

  • Sowbugs and pillbugs are the only crustaceans that have adapted to a life on land.
  • They are oval in shape, convex above, and flat beneath. They are gray in color, and 1/2 to 3/4 inch long. Sowbugs have two small tail-like appendages at the rear, and pillbugs do not.
  • Pillbugs can roll up into a ball, but sowbugs cannot.
  • Sowbugs and pillbugs live outdoors and like moist locations, such as under objects and plant debris.
  • They are beneficial decomposers, feeding on decaying organic matter in the garden. 

sowbug and pillgug illustration


  • They may invade damp basements and the first floors of houses.

  • They can be controlled by modifying conditions that are favorable to their development immediately outside the home.

  • Remove hiding places like stones or boards as well as leaves, plant debris, or mulch close to the foundation of your home. 

  • Properly ventilate basements and crawlspaces to eliminate excess moisture.

  • Repair and seal cracks and openings along foundation walls, doors, and windows. Tighten up door and window openings with weather stripping.

  • Escort visitors outside. Typically pillbugs and sowbugs dry out quickly and die indoors.

    Rev. 2020

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