Sowbugs

General Facts & Information

Two similar species in the class Isopoda, Porcellio laevis and Porcellio scaber, are classified as sowbugs and common in the US. Often thought to be insects, sowbugs are actually land-dwelling crustaceans that share closer ties to lobsters and crawfish. Long and half-cylindrical in shape, sowbugs look similar to pill bugs. The main difference between the two is the pill bug can roll into a ball, whereas the sowbug cannot. Though unable to roll up, the sowbug carries a host of ball-related nicknames like roly-poly, roll up bug, armadillo bug, and pea bug.

Appearance & Identification

What do sowbugs look like?
The half-cylindershaped sowbug measures between 1/4 of an inch and 1/2 an inch in length. The crustacean features a hard shell made up of segmented plates that appear dark gray or brown in color. Directly after molting, sowbugs may exhibit a purple or bluish hue. Like most crustaceans, sowbugs feature two pair of antennae, with one pair distinctively longer than the other. The sowbug walks on seven pairs of legs located on its underside and hidden by its shell. A paired tail, or uropoda, sticks out from the back of the abdomen and becomes visible when looking down at the creature. Plate-like gills on the underside of the abdomen allow the creature to breathe by extracting oxygen from water.

Habits/Habitat

Sowbugs need moist, cool habitats to survive. Semi-aquatic environments, such as creek beds and river banks, commonly serve as home to the crustaceans. Typically found under rocks and logs, sowbugs feed on the fungus and decaying material of their surroundings. Protected areas, like mulch, boards, flower pots, and ivy, may serve as suitable habitats as well. The crustaceans typically remain hidden during the day to avoid drying out but may emerge after a heavy rain or during overcast conditions. During the cold winter months, sowbugs remain inactive until temperatures increase. Preyed upon by spiders, centipedes, and ground beetles, the crustaceans may emit foul-smelling chemicals as a defensive response.

Diet

What do sowbugs eat?
Important in natural ecosystems, sowbugs consume decaying organic/plant material and fungi. Equipped with chewing mouthparts, sowbugs effectively dispose of rotting organic matter in a relatively short time. On rare occasions, sowbugs feed on young seedlings of plants and roots. Ripe fruits and vegetables that touch damp soil can also be eaten by the crustaceans. Fruits consumed by sowbugs may include strawberries, cucumbers, melons, and squash.

Reproduction

The sowbug life cycle begins with eggs, which the female carries around inside of her for several months. Once eggs hatch, the young remain inside the mother during early development and leave at their own will. After leaving, the young undergo 10 or more molting stages in which they shed their hard skins. Developing sowbugs resemble adults but appear smaller in size. Full development into adulthood takes approximately a year. However, most developing sowbugs do not survive the early stages of the life cycle and usually die by desiccation. Sowbugs that reach adulthood live for two or more years and may undergo several irregular molts.

Problems Caused by Sowbugs

Though sowbugs primarily feed on rotting plant material, the crustaceans may also eat young plant seedlings and roots. When abundant, sowbugs may prove troublesome to farmers and gardeners. On occasion, sowbugs may feed on ripe fruits and vegetables that happen to rest on damp soil. The crustaceans cause no harm to property in the home and cannot contaminate food, but their appearance in the home may distress inhabitants.

Signs of Infestation

Sowbugs may show up in damp basements, crawlspaces, and ground levels of homes. Finding live sowbugs on walls, in corners, and on floors indicates their presence and a potential moisture issue. Dried up bodies of the crustaceans can also alert homeowners to their presence inside the home. When found in the home, larger populations are usually found in the soil surrounding the residence.

Prevention

Eliminating conducive conditions to sowbug populations (reducing moisture) remains the key to sowbug prevention. Keeping the home free of moisture reduces the likelihood of sowbugs taking up residence. Running dehumidifiers in damp basements usually serves as the best approach to making a habitat unfavorable to sowbugs. Homeowners also want to keep organic materials like firewood outside of the home and garage. Additionally, leaf debris, compost piles, and vines should not contact the home.

Gardeners growing plants susceptible to sowbug attack should avoid using organic mulches, which give the critters moist shelter. Coarse mulch that allows airflow and black plastic mulch that absorbs sunlight dry quickly and will not support sowbug breeding. When using mulch, homeowners should mulch areas that remain dry and can be reached by sunlight. Ground frequently watered by sprinkler irrigation may support the crustaceans. Watering early in the day so the soil surface dries by night often eliminates habitats for the pests. Drip irrigation also curbs the possibility of sowbug populations becoming problematic. To keep sowbugs from feeding on ripe fruits and vegetables, gardeners should elevate the plants so the maturing produce does not make contact with the ground.