Sowbugs (Oniscus asellus) are an introduction from Europe. Although they live on land, they are crustaceans and are related to shrimp and lobsters. Sowbugs have seven pairs of legs, a series of armour plates covering the back and may be up to 15 mm (half an inch) long. They are greyish brown in colour and flat.
Sowbugs are a common sight in yards and homes in the Edmonton area. They usually cause the most concern when found crawling in the home, especially in large numbers. They are harmless, incapable of biting or stinging. They will not infest your food, clothing, or damage your home. Sowbugs found alive in your house have typically not been there very long, and will quickly dehydrate. They feed on decaying matter, so there is little concern for plant health in your yard.
What You Can Do
Sowbugs typically live in damp areas and feed on decaying plant material. Removing any grass clippings, mulch, rotting wood and leaf litter around the foundation of your house will help keep the area dry.
Removing logs, boards or boxes under which sowbugs hide will also help.
Basements and crawl spaces should be kept dry and free of any food material for sowbugs. Foundations, doors and windows should be properly sealed to prevent entry. Sweep or vacuum any sowbugs that may still wander in. Spraying is not usually required.