Sowbugs and pillbugs, sometimes called "woodlice," live outdoors, but they may occasionally enter homes in damp areas such as basements, first floor levels and garages. These creatures are a nuisance by their presence; they do not bite humans nor damage structures or household possessions. However, if present in large numbers, they can feed on young plants in greenhouses. Some may crawl into swimming pools and drown, causing complaints. Those that wander into homes usually die in a few days unless they find a moist place near a leaky pipe or in a damp basement, bathroom or laundry room.

Identification

Sowbugs are oval or slightly elongate with a flattened body and up to 3/4 inch long. They are wingless, brownish or slate gray, and possess well-developed eyes, seven pairs of legs and overlapping "armored" plates that make them look like little armadillos. Sowbugs have two tail-like structures on the rear end. Pillbugs are similar, except they lack the tail-like appendages and can roll up into a tight ball. Both are slow-moving crustaceans closely related to crayfish, shrimps and lobsters but not insects. The young resemble the adults, except they are smaller and lighter in color.

Life Cycle and Habits

Both sowbugs and pillbugs mate throughout the year, with most activity in the spring. The female carries the eggs, numbering from 7 to 200, in a brood pouch on the underside of her body. Eggs hatch in three to seven weeks and the young are white-colored. They remain in the brood pouch for six to eight weeks until they are able to take care of themselves. There may be one to two generations per year, with individuals living up to three years depending on weather conditions.

These creatures live outdoors, feeding on decaying organic matter and occasionally young plants and their roots. They may become pests in and around homes where flower bed mulches, grass clippings, leaf litter, rotting boards, trash, rocks and pet droppings are present. Adequate moisture is essential for their survival, and they group in masses to reduce water loss. On a hot day, they remain under objects on the damp ground and are active only at night due to lower temperatures and more humid conditions. They become inactive during the winter months except in heated buildings such as greenhouses.

Control Measures

Since sowbugs and pillbugs require moisture to survive, it is important to keep the house and outside as dry as possible.

Prevention

Remove hiding places such as piles of leaves, grass clippings, mulch in flower beds, fallen fruit, pet droppings, boxes, boards, stones and other debris from the foundation walls, doors, basement windows and other points of entry. Properly ventilate basements and subfloor crawl spaces to eliminate excess moisture. Repair and seal cracks and openings in the foundation wall, around doors, and around basement windows with caulking compound and weather stripping. Drain standing water and moist areas near potential points of entry.

Indoors, the use of fans and dehumidifiers will help dry out the basement and other damp rooms. These creatures can be collected with a broom and dustpan, vacuum cleaner or other mechanical means and discarded. Insecticide sprays usually are not needed indoors since sowbugs and pillbugs dry out quickly and die. However, household contact or residual sprays are sometimes used.