How to Manage Pests

Pests in Gardens and Landscapes

Sowbugs and Pillbugs

Sowbugs and pillbugs are not insects but soil-dwelling crustaceans in the Isopod order, more closely related to crayfish than to insects. Isopods have a hard, shell-like covering that is made up of a series of segmented plates. Some isopods roll up into a ball when disturbed and are called pillbugs. Isopods have seven pairs of legs and are dark gray or brown but may be almost purple or blue just after molting.

Damage

Sowbugs and pillbugs feed primarily on decaying plant material and are very important in the process of decomposing organic matter in the garden. However, they occasionally feed on seedlings, new roots, lower leaves, and fruits or vegetables lying directly on the soil or near a damp soil surface.

Solutions

Limit moisture and decaying matter. Try to water 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 sowbugs from becoming serious problems. Black plastic mulch may be more effective at discouraging sowbugs than white or clear plastic are because it gets hotter.

Adult pillbugs
Adult pillbugs

Adult sowbug
Adult sowbug


Statewide IPM Program, Agriculture and Natural Resources, University of California
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