Sowbug & Pillbug
Porcellio laevis, Porcellio scaber,and Armadillidium vulgare
What are Sowbugs and Pillbugs?
Sowbugs and pillbugs, also known as “woodlice,” are an outdoor pest; however, they sometimes invade basements or the ground levels of buildings. Sowbugs that do make it inside face imminent death unless they find a moist place to live, such as near a leaky pipe or in a damp basement, bathroom or laundry room. These creatures are a nuisance by their presence only and pose no threat to humans– they do not bite or cause any structural or household damage. The only danger they pose is to young plants in greenhouses, which is something that they feed on. Some pool swimmers may find them a nuisance, as the bugs may jump in and drown, leaving behind their unsightly corpses.
These creatures are actually slow-moving crustaceans. They are closely related to lobsters and shrimp, but do not taste nearly as good.
Can you tell me a bit about their biology?
Sowbugs are oval-shaped or slightly elongated with a flattened body and measure up to 3/4″ long. They possess no wings, and are brownish or slate gray in color. Other outstanding features include well-developed eyes, seven pairs of legs and overlapping “armored” plates that make them look somewhat like miniature armadillos. Sowbugs have two tail-like structures on their rear end. Pillbugs are similar, except they lack tail-like appendages and have the ability to roll up into tight balls. Both are crustaceans. Young sowbugs and pillbugs resemble the adults, except they are smaller and lighter in color.
What’s their behavior like?
Both sowbugs and pillbugs mate throughout the year, with most activity occurring 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 3 to 7 weeks and the young are white-colored. They remain in the brood pouch for 6 to 8 weeks until they are able to take care of themselves. One to two generations are born per year, and individual bugs live for up to three years.
Sowbugs and pillbugs like damp, dark conditions. They will stay underneath logs, flower bed mulches, grass clippings, leaf litter, rotting boards, trash, and rocks and hang around pet droppings. Since adequate moisture is essential to their survival, they sometimes need to group together to reduce water loss. Sowbugs are more active at night than during the day.
During the winter months, they become inactive unless they have access to a heated building or greenhouse.
What do they eat?
Sowbugs and pillbugs feed on decaying organic matter and, occasionally, young plants and their roots.