Sowbugs (Pillbugs) Natural Controls

Sowbug pillbug

Sowbugs are hard shelled land-dwelling crustaceans. They are not insects.

Adult sowbugs are slate gray or brown ¼ to 5/8 inch long with jointed armor segments and seven pairs of tiny legs. A sowbug resembles an tiny armadillo.

Sowbugs eat decaying plant and other organic material in the garden including decaying vegetables and fruits. Sometimes they will chew on seedlings and strawberry fruits, but generally they do not threaten crops and are important to the process of decomposition of organic matter.

Some species of sowbugs that roll up in a ball when disturbed are called pillbugs or roly polys. But not all sowbugs can do this. Generally, all sowbugs are also referred to as wood lice.

Sowbugs reproduce both sexually and asexually. An adult female sowbug keeps eggs on the underside of her body until they hatch. Nymphs are small and white but otherwise look like adults sowbugs. Nymphs grow to adults by progressively shedding their shell-like exoskeleton in two stages, first the back half, then the front half. After molting, sowbugs appear purple or blue.

Sowbugs are active and feed at night. They breathe through gills and require a moist environment. During the day they hide in dark, moist places, under boards, rocks, mulch, and decaying plants.

Sowbugs are found throughout United States.

Target Plants: Sowbugs  feed on decaying plant material. They occasionally feed on seedlings, new roots, and the lower leaves of plants that may be laying on the ground. They feed decaying vegetables and fruits laying on the ground.

Feeding Habits and Damage: Sowbugs will chew decaying plant leaves and fruit. They will also chew strawberry fruits laying on moist soil. The damage sowbugs inflict is not severe. Because sowbugs eat decaying organic matter, they assist in the natural composting process. They also turn the soil and aid in soil aeration which is an aide to plant roots.

Organic Controls: There are several ways to control sowbugs:

  • Limit excessive soil moisture in the garden to limit the number of sowbugs. Water in the morning so that plants and the soil surface can dry out by night.
  • Encourage air circulation in the garden; use spun poly or plastic sheet mulch to keep crops off the ground or grow plants on stakes and trellises.
  • To keep sowbugs from crops sprinkle diatomaceous earth around the base of plants and building foundations where bugs congregate.
  • Trap sowbugs under stones or boards, then remove them to another location or destroy them.
  • Make paper traps painted with a sticky coating such as Tanglefoot; then fold them tentlike and place them around the garden.

Scientific Name:  Family Armadillidae

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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