Silver Soil Bugs

Isopods often are silver or gray in color.

Digging in the garden can turn up some very strange insects. Grubs, millipedes, many varieties of beetles and even those silver-armored creatures, the isopods. Isopods (commonly known as pillbugs, sowbugs, roly-poly bugs or woodlice) are not insects at all, but a land-dwelling crustacean. Their armor plating can vary in color from white to black and even shades of brown, but most are gray or silver.

Crustaceans

While isopods are found crawling around in the soil alongside many kinds of insects, they are in fact, crustaceans like crabs and lobsters. Sowbugs and pillbugs are some of only a few crustacean species that can exist on land. These 1/2-inch long creatures feed on decaying matter like their aquatic counterparts and breathe through gills. If soils are too dry, these isopods will seek more moist locations or die.

Sowbugs and Pillbugs

Sowbugs (Porcellio laevis) and pillbugs (Armadillium vulgare) are different creatures entirely, though both members of the order Isopoda. Because the two crustaceans are more similar than different, they are often lumped together when discussed. The pillbug has the unique ability to roll itself into a ball when it anticipates danger; sowbugs lack this ability. Sowbugs also have an additional pair of appendages on their tail-end called uropods.

Reproduction

Isopods do not reproduce like insects. The female isopod has specialized structures on her underside that hold her eggs. When the eggs hatch, about two months after deposit, the young will remain in the pouch for six to seven weeks before emerging. Once emerged, baby isopods part ways with their mothers and never return. Each female isopod can bear between 25 and 200 eggs and up to three generations per year, depending on the climate.

Damage

Generally, isopods are not considered to be dangerous to gardens. They are frequently found hiding in moist places, such as under mulches or garden rocks. Isopods generally feed on decaying matter but will feed on the roots of seedlings if other food is not readily available. They occasionally find their ways in to basements and crawl spaces but do not damage property or bite.

References

• University of Arizona; Isopod, Pillbug, Sow Bug Information; 1997
• North Carolina Cooperative Extension; Pillbugs and Sowbugs; James R. Baker, et al.; 2001
• University of California Integrated Pest Management for the Home Environment: Sowbugs and Pillbugs
• Texas Agrilife Extension; Sowbugs, Pillbugs; B. M. Drees, et al.; 1999