Pillbugs and Sowbugs

Pillbugs and sowbugs are crustaceans pests that are more closely related to shrimp and crayfish than to insects. They are dark slate grey and measure approximately 2 cm in length. Pillbugs and sowbugs are very similar in appearance. The biggest difference between the two species is that pillbugs can roll into a ball when alarmed and sowbugs cannot while   the sowbug has two tail-like appendages that the pillbug does not.

Habits & Behaviours

Pillbugs and sowbugs are common pests found throughout Ontario. They typically prefer to live outdoors in damp dark places, but will at times invade damp basement areas as well as the first floors of residential, recreational/cottage, and commercial properties. Both species need to stay moist in order to survive so they actively scavenge for decaying leaf litter and vegetable matter only in the cool of the night. To prevent dehydration during the day, they seek dark, moist areas to hide and rest. Pillbugs and sowbugs often gather in groups, huddling together to reduce evaporation, some even burrowing into the ground to keep their gills wet. Gills are the primary breathing apparatus for all crustaceans and must remain moist in order to function.

Complaints & Destruction

Though generally not a destructive pest, pillbugs and sowbugs in large numbers can do significant damage to plants, gardens, and crops. Like other garden pests, they’re feeding can lead to a decrease in the annual harvest of any crop. Once established on the property, pillbugs and sowbugs will occasionally move inside to avoid excessive cold or heat. When this occurs, it is usually a good indication that there could be a serious moisture problem and they are present in large numbers in the soil and under plants immediately outside the house.

Major Risks & Dangers

There are no real risks or dangers associated with pillbugs and sowbugs. They do not bite or sting and cannot damage household furnishings or property.

Reproduction & Life Cycle

Pillbugs and sowbugs breed in March and April. Two to three broods are raised each year, each brood consisting of 30-40 young. The female carries the eggs in her pouch until they hatch and then continues to carry the young for six to eight weeks after hatching, if necessary. Both the female and male pillbugs and sowbugs are active parents, the male guarding the family’s burrow, while both parents gather food and clean the burrow of debris. It takes approximately one year for the young to become adults.

Eating Habits

Pillbugs and sowbugs are detritivores and primarily feed on decaying vegetable matter, new roots and, the tips of green leaves.

Treatment & Prevention

To eliminate and reduce the risk of pillbugs and sowbugs invading your residential, recreational/cottage, or commercial properties, treatment and exclusion is the best prevention.

Greenshield Pest Control Inc. can provide you with many treatment, exclusion, and prevention solutions.


If you suspect a pillbug and sowbug infestation within your residential, recreational/cottage or commercial properties, it is best to let the professionals do the job of safely removing the insects. Please contact us today or see our Pest Control Services section for further information on the types of services and insect pest solutions we can provide.

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