Sowbugs
Oniscidea
📖 Description
Sowbugs and pillbugs are terrestrial crustaceans, not insects, that are primarily beneficial decomposers in the garden ecosystem. They feed on decaying organic matter, recycling nutrients back into the soil. However, when populations are high or when their preferred decaying food is scarce, they may feed on tender seedlings, young roots, and fruit resting on the soil surface. They require moist conditions to breathe through gill-like structures and are strictly nocturnal feeders. Their damage is most common in overly wet gardens, greenhouses, and containers with consistently damp soil. In most cases, their beneficial role as decomposers far outweighs the minor damage they cause to plants.
⚠️ Symptoms to watch for
- Irregular chewing damage on low-hanging fruit and tender seedlings,Holes in ripe strawberries resting on soil surface,Chewed roots on young transplants,Gray oval bugs visible under pots, mulch, and debris,Damage concentrated in moist, shaded areas near ground level
🩹 Treatment
- Remove hiding places like boards, stones, and dense mulch (organic),Set out rolled-up newspaper or potato traps and dispose daily (organic),Apply diatomaceous earth around seedling bases (organic),Allow soil surface to dry between waterings (organic),Use iron phosphate bait around affected plants (organic),Apply permethrin-based granules to soil surface (chemical)
🌿 Organic treatments
- Remove hiding places like boards, stones, and dense mulch,Set out rolled-up newspaper or potato traps and dispose daily,Apply diatomaceous earth around seedling bases,Allow soil surface to dry between waterings,Use iron phosphate bait around affected plants
🧪 Chemical treatments
- Apply permethrin-based granules to soil surface
🛡️ Prevention
- Reduce moisture levels by watering in the morning and improving drainage,Keep mulch away from direct contact with plant stems,Elevate fruit off the soil surface using straw or racks,Remove decaying plant material and debris from garden beds,Start seedlings indoors and transplant after they are established,Create a dry barrier of gravel or sand around vulnerable plants
🪴 Affected plants
- Seedlings,Tender Roots,Strawberries
🦋 Natural predators
- Spiders,Centipedes,Birds
🌱 Host plants
- Various seedlings,Decaying matter
🔄 Lifecycle
- Females carry 20-50 eggs in a fluid-filled brood pouch (marsupium) on their underside for 3-7 weeks until they hatch.
- Young emerge as miniatures of adults and molt regularly, adding segments and legs.
- They undergo 10-20 molts over their 2-3 year lifespan.
- Females can produce 1-3 broods per year.
- They are nocturnal and require high humidity to survive.
- Development slows in cold weather but they remain active year-round in moderate climates.
📅 Season
- Year-round (most active in cool, moist conditions)
🔎 Appearance
- Oval, gray to dark gray crustaceans with segmented, armor-like bodies and seven pairs of legs.
- Sowbugs (pillbugs) can roll into a ball when disturbed; true sowbugs have two tail-like appendages and cannot roll up.
- They are the only crustaceans adapted to living entirely on land.
💥 Damage level
- Low
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- North America
- Europe
- Asia
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