Roly Poly Enclosure: How to House Isopods and Pill Bugs Right

Roly polies — those small round crustaceans that curl into a perfect ball when touched — are one of the most universally recognized micro-animals from childhood nature exploration. As pets, they are beginner-friendly, surprisingly entertaining to observe, and serve as an excellent introduction to the broader isopod-keeping hobby.

This guide covers everything you need to set up and maintain a roly poly enclosure, whether you’re keeping them as pets in their own right or as the beginning of a more serious isopod collection.

What Are Roly Polies?

“Roly poly” is a common name for pill bugs — specifically Armadillidium vulgare, the most common pill bug species in North America and Europe. Unlike most isopods, Armadillidium species can fully roll into a complete sphere (conglobation) as a defense mechanism. This distinguishes them from pill millipedes (a different animal that looks similar) and from other isopod species like Porcellio that cannot fully roll.

Roly polies are terrestrial crustaceans, not insects — they’re more closely related to crabs than to beetles or ants. They breathe through gill-like structures that must stay moist, which is why they’re found in damp places: under rocks, in leaf litter, under logs.

Enclosure Setup

Container Choice

A clear plastic container with a secure ventilated lid is the standard roly poly enclosure. Options:

Deli cups (32 oz to 1 quart): excellent for a small starter group of 10–25 individuals

Clear plastic storage tub (6–12 quart): for a larger colony or more elaborate setup

Purpose-built isopod display containers: acrylic enclosures with mesh ventilation; more attractive but higher cost

Ventilation is essential. Add several small holes (1/8″ or smaller, covered with mesh) near the top of the container. Without ventilation, CO2 accumulates and humidity becomes stagnant.

Substrate

A 2 to 3 inch layer of moisture-retaining substrate is the foundation:

Coconut fiber (coco coir): holds moisture well, resists mold, provides excellent burrowing medium

Leaf litter: dried oak, magnolia, or beech leaves as the top layer; both a food source and a hide structure

Organic topsoil mixed with coco coir: good alternative if straight coco coir is unavailable

Moisture gradient: keep one corner or side slightly moist (spray with distilled water every 2–3 days) and let the other side dry out between mistings. Armadillidium species are more tolerant of drier conditions than Porcellio species but still need access to moisture.

Hides and Structure

Roly polies need hides for molting, moisture regulation, and the natural congregation behavior they exhibit. Options:

Cork bark flat pieces: excellent; provides humid microclimate underneath

Flat rocks or slate pieces: simulate the rocks they’re found under in nature

Dried leaves: layer generously over the substrate surface

Feeding Your Roly Polies

Roly polies are detritivores — they eat decomposing organic matter. In captivity:

Leaf litter: the primary continuous food source; replenish as leaves are consumed

Vegetables: cucumber slices, carrot pieces, sweet potato; remove uneaten fresh food after 48 hours

Dried mushrooms: a favorite supplement; nutritious and consumed enthusiastically

Cuttlebone: essential calcium source; keep one piece in the enclosure permanently

Overfeeding is the most common mistake: excess food molds in the humid enclosure. Feed small amounts and remove uneaten fresh food promptly.

Temperature and Humidity

Temperature: 65–78°F (18–26°C); room temperature is adequate in most homes

Humidity: moist corner 70–80%; dry corner 50–60%; Armadillidium tolerates drier conditions than most isopods

No supplemental heating required in most home environments

Starting Your Colony

Start with 10 to 25 roly polies. They can be:

Wild-caught from your garden: collect from under rocks, logs, or leaf litter in pesticide-free areas

Purchased from isopod hobbyist breeders: captive-bred colonies are cleaner and disease-free

Available from some pet stores (reptile sections) as “cleanup crew” isopods

Armadillidium vulgare has a slower reproduction rate than Porcellio species — don’t expect a population explosion in the first months. The colony will grow steadily over 6 to 12 months.

Roly Polies in Bioactive Terrariums

Armadillidium vulgare is used as a bioactive cleanup crew in terrarium setups, particularly in temperate-origin enclosures and arid setups where higher-humidity Porcellio species wouldn’t thrive. Their stable, moderate population growth rate means they won’t overrun an enclosure the way faster-breeding species can.

For bioactive terrarium use, see: Bioactive Terrarium Isopods: The Ultimate Setup Guide [Link to Article #22]

Frequently Asked Questions

Can roly polies be kept as pets?

Yes — roly polies (Armadillidium vulgare) are low-maintenance, interesting micro-pets that are particularly popular with children and naturalist hobbyists. They are harmless, easy to care for, require minimal space, and exhibit fascinating natural behaviors including the distinctive rolling-into-a-ball defense response.

Do roly polies need a heat lamp?

No — roly polies do not require supplemental heating in typical home temperatures. They thrive at room temperature (65–78°F) without any heat lamp or heat mat.

Can I keep roly polies with other isopods?

Yes — Armadillidium vulgare coexists well with other isopod species (particularly Porcellio species) and with springtails. Multiple isopod species in a bioactive terrarium create a more complete cleanup crew with broader ecological roles.