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Occasional Invaders

Sowbugs & Pillbugs

Armadillidium vulgare (pillbug), Porcellio laevis (sowbug)

Danger Level: 1/5Updated September 2026 · Boise, ID

IdentificationHow to Identify Sowbugs & Pillbugs

Quick Answer

Sowbugs and pillbugs (roly-polies) are crustaceans, not insects. They're closer cousins to shrimp and crabs than to anything else in your yard.

Full identification notes

Pillbugs roll into a ball when disturbed; sowbugs cannot. Both have segmented, oval bodies with seven pairs of legs and two tail-like appendages (more visible on sowbugs).

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Sowbugs & Pillbugs Behavior & Habits

Understanding how sowbugs & pillbugs behave helps prevent infestations

These creatures require moisture and die quickly in dry conditions.

More about their habits

They eat decaying plant material and are typically found in damp areas under debris, mulch, and stones. They enter homes seeking moisture when outdoor conditions become dry.

Sowbugs & Pillbugs Risks & Dangers

What sowbugs & pillbugs can do to your health and property

Health Risks

Sowbugs and pillbugs don't bite, sting, or transmit diseases.

Property Damage

No damage to structures or belongings.

Full health and property details

Health Risks

They're completely harmless to humans and pets.

Property Damage

They may occasionally damage tender plant seedlings but are primarily decomposers of dead plant material.

Signs of Sowbugs & Pillbugs Infestation

Look for these indicators in your home

Signs You Have Sowbugs & Pillbugs

What homeowners spot first

  1. Gray oval creatures under pots or debris
  2. Roly-poly bugs curling into balls when poked
  3. Activity in damp basement and crawlspace areas
More signs to look for
  1. Concentrations under mulch within 6 inches of the foundation
  2. Dead ones along garage door tracks and basement window wells

Sowbugs & Pillbugs in Boise & the Treasure Valley

Most of our sowbug and pillbug calls in the Treasure Valley land between late June and September, when the summer dry-down pushes them off the lawn and toward the cool, damp slab at the foundation.

More on what we see locally

We see the heaviest pressure in canal-side neighborhoods like Garden City, the Boise Bench, and Eagle Island, plus older Nampa and Caldwell homes where heavy bark mulch sits pushed right up against the stem wall. They almost always turn up in the same three places: under mulch within 6 inches of the foundation, behind landscaping rock that traps irrigation moisture, and on basement floors right after a heavy sprinkler cycle.

Our Solution

How We Handle Sowbugs & Pillbugs

What our approach looks like

We work a 3-foot dry barrier around the foundation, pull mulch back from the stem wall during the inspection, and treat the harborage spots right up against the house (under rocks, behind hose bibs, at downspout splash zones).

Our full approach

Indoor stragglers get spot-treated, but the real fix is cutting off the outdoor population. Most basement activity stops within a week once the perimeter is treated and the moisture source is identified. Your first visit is $49 with quarterly service.

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How to Prevent Sowbugs & Pillbugs

Steps you can take to reduce the risk of infestation

  1. Reduce moisture around foundation
  2. Keep mulch at least 6 inches from foundation
  3. Remove leaf litter and debris near home
More prevention steps
  1. Fix leaky outdoor faucets
  2. Improve drainage around home
  3. Ventilate crawlspaces and basements

Sowbugs & Pillbugs Questions Answered

Common questions about identification, prevention, and treatment

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Are roly-polies harmful?

Quick answerNo.

Pillbugs (roly-polies) are completely harmless. They don't bite, spread disease, or damage property. They're actually beneficial decomposers that help break down dead plant material in gardens.

Why are they in my basement?

Quick answerSowbugs and pillbugs need constant moisture to survive.

If they're showing up in your basement, you have a moisture problem somewhere. The usual culprits we find in Treasure Valley homes are a slow foundation leak, an over-irrigated flower bed against the stem wall, or water wicking through a cinder-block wall during the summer watering season.

Are these actually bugs?

Quick answerNo!

Sowbugs and pillbugs are crustaceans, closely related to crabs, lobsters, and shrimp. They breathe through gill-like structures, which is why they require moist environments.

Think You Have Sowbugs & Pillbugs?

Call and we'll talk through your options. We usually get out within 24 to 48 hours.

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