Adults are up to 5/8” long, flat or hollow beneath and are dark to slate gray in colour. Sowbugs have 7 pairs of similar legs, 2 pairs of antennae, 1 tiny, the other readily visible. They have 2 tail-like appendages which project out from the body on the rear end and are also capable of rolling into a loose ball when disturbed.
The eggs are deposited and hatch within the brood pouch on the underneath side of the body. It usually takes about 45 days for the eggs to develop, hatch, and the young sowbugs to emerge from the pouch. The number of young per brood averages about 24 (range to 88) and there are 1-3 broods per year. Young sowbugs molt every 1-2 weeks and reach adulthood in about 20 weeks. Adults may live about 2 years. Sowbugs are confined to areas of high moisture because they lack both a closing device for their respiratory system and an outer waxy layer on their exoskeleton to prevent excessive water loss. Their nocturnal habit helps to reduce water loss.
Because water loss is such a problem, sowbugs are inactive during the day and remain hidden under objects to reduce moisture loss. During the day, they can be found around buildings in such places as under trash, boards, rocks, flower pots, piles of grass clippings, flower-bed mulches, and other decaying vegetation. Occasionally they will enter buildings via door thresholds, especially homes with sliding doors on ground level. Indoor invasion typically means that there is a large population immediately outside the building. Usually they do not survive indoors for more than a couple of days unless there are moist conditions and a supply of food present. Sowbugs are scavengers and feed on decaying organic matter, usually plant material. They cause no damage but are considered a nuisance pest indoors. Outdoors, they occasionally injure young plants.
The key to controlling sowbugs is to reduce or eliminate the moist areas. For example, remove piles of grass clippings and leaves, lumber, firewood, and flower pots off the ground, and provide adequate ventilation in crawl spaces. Indoors they can be removed with a vacuum. Application of appropriately labelled residuals can be made to the exterior foundation walls, perimeter flower and/or ornamental planting beds, unfinished basements, and crawl spaces.