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Sow Bug (Porcellio spp)

Sow bugs are not insects but are in fact soil-dwelling crustaceans, more closely related to crayfish than to insects. They have seven pairs of legs and may be dark gray, brown, purple or blue.

Where do they live?

Sow bugs are most active at night. They spend daylight hours in moist, dark habitats. During the day, they can be found hidden underneath rocks, in ground litter, or between the edges of moist grass and sidewalk areas. 

How do they live?

Females have marsupial-like pouches on the undersides of their bodies that can hold up to 100 developing eggs.  Full development to an adult takes about 1 year. The life span of sow bugs is about 3 years. Adults are between 6 mm and 13 mm long.

How do they affect us?

Sow bugs do not bite, sting or transmit disease.

They are omnivores, mainly feeding on dead or decaying plants and animals, and are therefore considered somewhat beneficial in gardens for their role in overturning soil and producing compost.  However, they have been known to feed on tender plant tissue, seedlings, stems and roots of young garden vegetables and other plants lying directly on the soil or near a damp soil surface.

How do we control them?

The presence of moisture and decaying matter must be limited. Watering should be done early in the day so the soil dries by evening. Using raised beds or planting boxes, plastic mulch, and drip or furrow irrigation instead of sprinklers usually keeps sow bugs from becoming a serious problem.