Isopods (Pillbugs & Sowbugs)

Overview

Terrestrial isopods are crustaceans, not insects ¹². Pillbugs (family Armadillidiidae) and sowbugs (family Porcellionidae) are the most familiar ¹². They have become popular pets ¹:

• Native species can be collected around the home and kept in terrariums.
• Tropical species such as the "dairy cow" and "amber ducky" isopods are now sold in pet stores.
• Cleanup crews. Isopods also clean up vivariums by breaking down plant matter and waste ¹⁶.

Adults are about ⅓ to ¾ inch long ¹². They live about 2 to 5 years ¹². They don't bite or sting and are harmless to people and pets ¹³.

This is a group guide. University extension services cover the biology of pillbugs and sowbugs well, but no veterinary care sheet covers isopods as pets. The care below follows that biology plus university classroom-habitat guidance ⁴⁵. As the University of Kentucky notes, each species may need different husbandry, so research the one you keep ¹.

Natural history

Isopods have seven pairs of legs, a small head and abdomen, and seven overlapping thoracic plates ¹².

• Pillbugs can roll into a ball, which earns them the name "roly-polies" ¹.
• Sowbugs have two tail-like appendages (uropods) and run instead of rolling ¹².
• Freshly molted isopods may look bluish or purplish ².

They live or die by moisture. Isopods breathe through gill-like structures and need damp surroundings ⁵. Rolling up is a defense and also helps them retain water ¹. They are mostly nocturnal and hide by day in leaf litter, mulch, soil and under stones, boards or logs ¹³⁴.

Isopods are detritivores. They eat fungi and decaying plant matter and occasionally tender plants ¹²⁴.

Enclosure

• Container. A lidded container with small air holes works ⁴. A terrarium works too ⁵.
• Placement. Keep it in a cool, dark place away from direct sunlight ⁴.
• Moisture gradient. Provide a moisture gradient, damp at one end and drier at the other, so the isopods can regulate themselves ¹.
• Cover. Add natural hiding places such as rocks, bark, twigs and leaves ⁴⁵.
• Groups. Isopods huddle together ⁴ and are kept as colonies ⁴⁵.

Temperature & lighting

Keep them cool and dark, away from direct sun ⁴. Isopods avoid dry air and extreme temperatures ⁴. No special lighting is needed. They are nocturnal and seek dark places ¹⁴.

Humidity

Moisture is the single most important factor ¹⁵.

• Keep it damp, not wet. Spray the container often so it stays moist but never wet ⁵.
• Damp paper towel. A folded damp paper towel on the bottom, rewet daily, also holds moisture ⁴.
• Dry spot. Always leave a drier area as part of the gradient ¹.

Without high moisture, isopods can hardly survive ¹.

Substrate

Use a few inches of natural or potting soil covered with leaf litter and a few pieces of bark, preferably oak ⁵. The University of New Hampshire suggests sand on one side and soil on the other for a classroom habitat ⁴.

Diet & supplementation

• Staple. Leaf litter and decaying wood or plant matter, which isopods break down naturally ¹²⁵.
• Extras. Small bits of carrot or apple ⁵, or carrot shavings and lettuce ⁴.

Handling & temperament

Isopods are harmless and can't hurt you, but you can easily hurt them ⁴. Move them with a plastic spoon or a craft stick, staying close to the ground in case they fall ⁴.

Health

Common issues

• Drying out is the main risk ¹³. A dry enclosure is quickly fatal.
• Too wet can also cause problems. Moist, not wet, is the goal ⁵.
• Molting. Isopods molt as they grow. Freshly molted animals are pale or bluish until the new covering hardens ².

When to see a vet

Our sources contain no veterinary guidance for isopods. Colony problems are usually habitat problems, so check moisture, ventilation and food first ¹⁵. If you need help, an exotics veterinarian or a university extension office are good places to ask.

Breeding overview

Females carry eggs and young in a brood pouch (marsupium) on the underside. This is a form of parental care ¹². Males have copulatory organs on the front underside of the thorax ². Common species have about 1 to 2 broods a year of about two dozen young ¹. Young emerge pale yellow to whitish, about 1/12 inch long ². They molt about every 1 to 2 weeks as they grow ² and mature in about 2 to 3 months ¹. A well-kept colony will show molting and young over time ⁴.

Legal & ethics

Many native pillbugs and sowbugs can be collected around your home ¹. Handle them gently with a spoon or stick ⁴. Research a species before you buy it, because husbandry varies ¹.

Sources

1. Sowbugs & Pillbugs · University of Kentucky Entomology
2. Pillbugs and Sowbugs · University of California Statewide IPM Program
3. Sowbugs & Pillbugs · Clemson University Home & Garden Information Center
4. Pillbugs: An interactive investigation into animal behaviors [STEM Activity] · University of New Hampshire Extension
5. Designing your very own science experiment lesson · University of California Museum of Paleontology (Understanding Science)
6. Poison Dart Frog Care · Tree of Life Exotic Pet Medical Center

Last reviewed 2026-10-24 by Novel Fauna. This guide is general husbandry information, not veterinary advice. When an animal is sick, see a veterinarian experienced with exotic animals.

Revision history

1. 2026-10-24 Library complete: 20 more cited guides (70 total), Invertebrates group, care targets migration 0020, source title fixes 5cf06a2

Evidence grades: Novel Fauna editorial: source classification, not yet expert-reviewed, 2026-10-25. What the grades mean.

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