Sowbugs and pillbugs are commonly found outdoors in South Carolina, especially under rocks and boards. They are not insects but are more closely related to lobsters and shrimp. They breathe with gill-like structures and must be in very moist areas to survive.
Sowbugs and pillbugs are similar in appearance. Both are oval in shape, have a rounded upper surface and a flat lower surface. They are gray, about 1/4 to 5/8 inch long and have body segments that resemble armored plates. They differ in that sowbugs have two tail-like structures at the rear, which pillbugs do not have. Pillbugs are commonly called roly-pollies because they roll up into a tight ball when disturbed. Sowbugs cannot roll up.
Both sowbugs and pillbugs have similar habits, biology and control. They live in areas of high moisture to prevent drying and death. They are active at night, feeding mainly on dead plant material and occasionally, young plants and their roots. During the day, they are inactive and can be found in moist areas such as under rocks, boards, mulch, leaf-litter and similar materials. They do not bite and are completely harmless to humans.
Although sowbugs and pillbugs normally live outdoors, they occasionally make their way into homes, especially damp basements and first floors of houses. This usually occurs in years when there has been a long, wet spring. Having many pillbugs or sowbugs invade a home is usually a sign that a large population exists outdoors. They may establish populations in house plants.
If sowbugs and pillbugs become a serious nuisance, the key to effective control is to reduce the moisture, hiding places and food sources that are needed for their survival. Remove leaf litter, mulch, lumber, rocks and similar materials from near the outside of the house. Properly ventilate basements and crawlspaces to decrease moisture. In addition, prevent them from entering the house by making sure windows and doors fit tightly, and cracks and crevices are caulked.
If necessary, an appropriately labeled pesticide can be applied to foundation walls, crawlspaces, unfinished basements and plant beds that border the home. Applications made to mulched areas should be made with just enough water for the insecticide to penetrate through mulch to reach the soil.
Insecticides are not recommended for indoor control because pillbugs and sowbugs dry out and die quickly inside a house. Indoors, they can be removed with a vacuum or broom and dustpan.
Originally published 05/99