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Isopod Care Guide

Beginner to advanced (species-dependent)

Last reviewed: July 2026

Overview

Terrestrial isopods — commonly called pillbugs, roly-polies, sowbugs, or woodlice depending on the species and region — are small land-dwelling crustaceans kept for three overlapping reasons: as a low-maintenance display animal, as a clean-up crew that manages leftover food and waste in humid terrariums housing other animals, and as a supplemental feeder for humidity-tolerant predators. Thousands of terrestrial species exist worldwide, but only a modest number are established in the hobby.

Most commonly kept species are hardy and forgiving once their enclosure is set up correctly, which is why isopods are often recommended as an entry point into invertebrate keeping. That said, isopods as a group span a very wide difficulty range — some species tolerate almost any reasonable setup, while others (particularly certain Mediterranean and desert species) require careful ventilation and moisture-gradient management and are better suited to keepers with some prior experience. See Difficulty below.

Compliance note: most isopod species sold in the trade in the United States are not native, and federal regulation (a PPQ 526 permit, administered by USDA APHIS) applies to importing, moving many species across state lines, or releasing them. Native species generally do not require this permit. Requirements can change and vary further by state, so verify current rules directly with APHIS and your state's department of agriculture before shipping, breeding at scale, or moving stock across state lines — see Additional Resources below.

Housing

Enclosure type matters more than size for most species. Plastic storage tubs, plastic "shoebox" containers, and glass terrariums or aquariums all work well. Avoid cardboard, wood, or masonite containers — they absorb ambient moisture, warp, and will eventually be chewed through.

Purpose-made small-animal habitats marketed for isopods or similar small pets are not a reliable substitute for a plain tub or terrarium; ventilation on many of these products is excessive for most isopod species and can lead to rapid drying out if watering is missed.

As a general starting point, lower ventilation is more forgiving for most commonly kept small-to-medium species — a solid lid with only the natural gap around the rim, or a shoebox lid with no added holes, is often enough. This isn't a universal rule: larger common species (Armadillidium vulgare, Porcellio laevis, and similar) generally do better with several small ventilation holes rather than a fully sealed lid, and a specific group of Mediterranean Porcellio species — P. expansus, P. flavomarginatus, P. magnificus, P. spatulatus, and P. werneri — are intolerant of continuous uniform moisture and need substantially more ventilation, plus at least half the substrate kept dry at all times (watered on one side or in specific spots rather than throughout). Don't assume "less ventilation is safer" applies to every species without checking; see Environment below for more on moisture gradients.

Substrate depth needed depends heavily on what you're setting up, and sources disagree somewhat on the specifics for a dedicated isopod culture tub. The source book behind most of this guide documents long-running, healthy cultures of many species kept successfully on as little as 1/8-1/2 inch (3-13mm) of substrate. Current mainstream hobby practice for a reserve culture bin more commonly lands around 1 inch (2.5cm) as a somewhat more forgiving baseline — deep enough to buffer a missed watering without wasting space. Either is workable; shallower setups just need more attentive watering. Deeper substrate (over roughly an inch/2.5cm) is specifically useful for burrowing species, but also holds more moisture at depth than the surface may suggest, and can give pests like nematodes more room to build up alongside other contributing factors like excess moisture and uneaten food — don't add depth "just in case" without a specific reason. None of this applies to a bioactive terrarium with live plants, which is a different situation and commonly uses substrate in the 3-5 inch (7.5-13cm) range to support root growth and burrowing space, independent of what the isopods themselves strictly require.

Suitable substrate materials include coconut fiber, peat, potting soil, sand, and composted leaf or wood material, often mixed together. Clay-heavy substrates can turn overly sticky and may slow the animals down. The goal is a substrate that holds some moisture without becoming waterlogged and that isopods can walk on and shelter in — they struggle on bare, smooth surfaces. These materials provide structure and moisture retention, not nutrition: the decomposing leaf litter and wood covered in Diet below is what most species actually eat, and plain potting soil or coconut fiber with no decomposing organic matter mixed in isn't a complete setup on its own.

Provide shelter: flat pieces of bark, cork bark, or wood that isopods can grip the underside of, or small hides like coconut huts. Avoid heavy rocks or logs that could crush animals if shifted during maintenance, and be cautious with heavily cracked or hollow wood, which is harder to fully clear of animals later if you need to. Cork bark tends to hold up longest against being chewed apart; softer woods degrade faster and should be replaced periodically.

If escape is a concern, isopods can climb smooth surfaces — aquarium silicone seams, thin condensation films — better than expected, especially small individuals. A thin band of petroleum jelly around the inside rim of the enclosure is an effective barrier.

Environment

Most commonly kept species tolerate a broad temperature range and do well at normal indoor room temperature (roughly 72-77°F/22-25°C); temperatures much above that are rarely necessary, and sustained heat above about 80°F/27°C can be harmful to some species. A smaller number of subtropical or Mediterranean species prefer the warmer side of that range, and a few cool-climate species are specifically heat-sensitive — check what a given species needs before assuming warmer is always better.

Humidity (water vapor in the air) and substrate moisture (liquid water content) are related but distinct, and airflow affects both — a humid room can still dry out an exposed animal quickly if there's a draft. Physical shelter (substrate, bark) protects against drying out more reliably than ambient humidity alone, which is part of why isopods spend most of the day hidden rather than out in the open.

Uneven humidity within a single enclosure is a real and under-recognized risk: if one side of a container sits against a cold exterior wall or near a heating vent, that side can dry out completely while the other stays wet, even though the enclosure's average moisture level looks fine. Rotating the container occasionally, or mixing the substrate periodically, helps prevent animals from becoming stranded on a bone-dry side — though mixing does disturb the substrate structure, so consider rotating the container instead of mixing around a visibly gravid female or when mancae are present. Beyond fixing an uneven-drying problem, keeping some deliberate variation in substrate moisture, rather than uniformly saturating the whole enclosure, is broadly useful for letting animals self-regulate. A specific, named group of species — including Porcellio marginatus and P. ornatus, alongside the Mediterranean Porcellio named under Housing's ventilation guidance — require an actual dry-zone/wet-zone split and do poorly if the whole substrate is kept uniformly damp; that stricter version is species-specific, not a universal requirement, but some moisture variation is good practice more broadly.

There is no single watering schedule that works for every enclosure. How quickly a container dries out depends on its placement (a shelf near an air vent dries faster than a shelf in a closed cabinet) and ventilation, so plan to observe and adjust rather than watering on a fixed calendar. As a rough diagnostic: needing to rewet more than about once every few weeks usually points to too much ventilation, while persistent excess moisture with unexplained deaths usually points to too little.

Lighting is not an important husbandry factor for most species — isopods are primarily active at night and tend to avoid bright light, and normal ambient room lighting is unlikely to meaningfully affect feeding or reproduction. Whether day length (photoperiod) acts as a reproductive trigger for a small number of notoriously hard-to-breed species is an open, unresolved question in the source material used for this guide — treat any claim that a specific lighting schedule will fix poor reproduction as unproven, not a reliable fix.

Diet

The most broadly useful staple food is brown, aged (decomposed) hardwood leaf litter — leaves that have been down for at least a few months, not fresh fallen leaves. A mix of leaf types (oak, maple, and similar) tends to work better than any single type, since tougher leaves support growth while softer leaves are eaten more readily. Fresh, undecomposed leaves are often ignored and can also contribute to mite population spikes from their higher nutrient content.

A variety of supplemental foods is commonly offered and generally well accepted in modest amounts: fish flakes or pellets, other pelleted small-pet foods, fruit and vegetable scraps (carrot, squash, melon rinds, apple), and occasional protein sources such as freeze-dried shrimp or krill. Avoid algae wafers and gelatinous cube-style foods, since their binder ingredients can trap small isopods.

Don't overfeed. Excess food that isn't consumed can rot, encourage mold and pest insects, and in enough volume can even deplete oxygen in a sealed enclosure. As a general rule, offer only what will be eaten within a few days, and remove anything perishable that hasn't been touched.

Calcium is biologically essential to isopods — their exoskeleton is mineralized with calcium carbonate, and calcium storage and redeposition are a real part of each molt cycle. Where this becomes genuinely debated, not just within this guide's source material but across the wider hobby, is supplementation: whether a captive culture needs a separate added calcium source (crushed eggshell, cuttlebone, chalk) on top of its regular diet. Some current commercial and hobbyist sources argue supplementation is necessary to prevent soft-shelled or failed molts; long-term, multi-species testing described in the primary source material used for this guide instead found no consistent link between added calcium sources and improved growth or reproduction, and one well-documented culture thrived for eighteen years with no calcium supplementation at all — the working explanation offered is that isopods already obtain and recycle calcium through their food, substrate, and their own shed exoskeleton (which most species eat), without needing a dedicated block. Some species do show clear interest in cuttlebone and will wear it down over time, but whether that reflects a genuine calcium need or a different attractant isn't established. Food quality and variety — particularly good leaf litter — appears to matter far more than calcium supplementation specifically in the testing this guide draws on. Offering a small calcium source as optional insurance is unlikely to cause harm, and may reasonably be worth doing given the current lack of consensus, but don't treat it as a guaranteed fix for a struggling culture.

For some species, particular foods — most often rotten leaf litter, and to some extent fresh hair algae — appear to function as a reproductive trigger, meaning a colony fed only fruit and dry pellets may grow and survive well but produce few or no offspring. This pattern is well-documented for some genera but explicitly does not hold for all of them, so if a culture isn't reproducing, food composition is worth reviewing but isn't guaranteed to be the cause.

Breeding

Isopods fertilize eggs directly (there's no external egg-laying), and females carry developing eggs in a marsupium — a brood pouch on the underside of the body formed from hardened plates. This pouch can be ruptured by rough handling or pressure, and eggs or young released prematurely will not survive, so avoid picking up or otherwise manipulating a visibly gravid female, including to check whether she's carrying eggs.

Time from egg to hatch generally runs three weeks to three months depending on species and temperature. The first free-living stage is called a manca — small, pale, and fragile — which molts again within hours and gradually develops adult coloration over subsequent molts. A pale or white animal isn't automatically explained by a recent molt the way it might be in some other arthropods: outside of the brief window during an adult's own molt (see Health), a pale animal is more often a manca, a genuinely white-colored morph, or a shed exoskeleton (or a dead, hollowed-out individual).

Time to reproductive maturity varies enormously by species — anywhere from about three months for some of the fastest-maturing small species to a year or more for many commonly kept species, and up to a few years for some larger or slower-growing types. Group housing with several adult females together tends to be more productive than keeping a single pair.

A small number of species reproduce by parthenogenesis (all-female, no males required), while the majority reproduce sexually — this is species-specific and shouldn't be assumed either way without checking the species in question.

Shelter availability can affect how many young survive to their first molt in species where adults provide some post-hatch care, since undefended young are vulnerable to being eaten by other tankmates once abandoned.

Color and pattern variants ("cultivars") traded in the hobby are, based on hobbyist breeding records reviewed for this guide, generally reported as simple recessive traits — a form that can potentially be isolated over a few generations from suitable founder stock. This is hobbyist breeding experience, not peer-reviewed genetics, and it does not hold universally: several documented attempts to isolate an unusual color form, in more than one species, instead produced entirely normal-colored offspring across multiple generations, meaning the original coloration either wasn't a stable heritable trait or the founder animals weren't genetically what they appeared to be. Treat any specific color-morph breeding claim as something to verify against your own results rather than a guarantee, and expect that isolating a genuinely new line — as opposed to maintaining an already-established one — is a multi-year project.

Common Problems

Grain mites are the most common invertebrate-culture pest generally, typically arriving on fresh (not aged) food. In established isopod cultures specifically, they're reported as less likely to reach the more damaging dispersal stage than in other invertebrate enclosures, but numbers can still climb to a nuisance level, particularly with overfed fresh produce. Shifting toward aged leaf litter and wood, and cutting back on fresh food, generally brings numbers back down.

Fungus gnats are a minor nuisance whose larvae feed on wet, uneaten leaf litter rather than on isopod waste itself — reducing how much fresh leaf litter is added at once, and ensuring good drainage, usually resolves them.

Mold on substrate, wood, or leftover food is common and usually harmless to isopods directly, though heavy fungal growth can physically trap small individuals, and substrate that's gone consistently moldy is worth refreshing.

A pink or salmon-colored microbial growth sometimes appears on damp surfaces or on dead isopods — commonly identified as Serratia marcescens (the same organism responsible for pink staining in damp household spots like shower curtains), though pink or salmon growth in general can have more than one cause and can't be reliably identified by color alone without lab testing. Treat any pink or salmon growth as contamination regardless of the exact organism: it's common in soil and water generally and difficult to fully prevent, but it can be harmful to humans — remove and dispose of affected material carefully, and wash your hands after handling it.

If you keep more than one isopod species, be aware that one species can gradually and competitively displace another sharing the same enclosure, particularly small, pale "micropod" species, which can be easy to overlook until well established. This isn't dangerous, just something to plan for if you want to keep species separate long-term.

For valuable or hard-to-replace stock, keeping two separate cultures under slightly different conditions is a simple way to protect against losing everything to a single enclosure problem, and makes it easier to diagnose what went wrong if one culture does decline.

Health

Molting happens in two separate phases in terrestrial isopods — the back (posterior) half first, followed by the front (anterior) half a few days later — which is unusual among arthropods and keeps the animal able to move throughout the process; this order and its advantages are confirmed in peer-reviewed literature, not just this guide's primary husbandry source (see Additional Resources). During this window it's normal for the freshly molted half to look temporarily paler, softer, or slightly different in texture than the half that hasn't molted yet, producing the classic "two-toned" look that alarms a lot of new keepers; this settles down within about a day or two as the new half matches the rest of the body. That's a different, temporary phenomenon from the manca/exuvia/dead-animal causes of paleness described in Breeding and the FAQ, and from a persistent, non-resolving color change, which is worth investigating further (see the iridovirus note below).

Isopods are physically fragile as individuals — excessive pressure during handling can cause fatal injury. The safest way to move isopods is to let them climb onto a piece of bark or wood and lift that out, rather than picking animals up directly.

It's normal, not a warning sign, for isopods to consume a dead or dying tankmate — this is ordinary scavenging behavior in this group, not a symptom of an unhealthy culture on its own. Injuries to a healthy, actively molting animal are rarely reported and usually only occur at very high population densities combined with insufficient food, where hungry animals can swarm toward an injured or otherwise compromised individual; most observed cases involve an animal that was already sick, injured, or dying before being scavenged, rather than a healthy animal being targeted outright. A consistent protein source (see Diet) is one practical way to reduce this pressure in a crowded culture, alongside simply reducing density.

Some injuries can heal or partially regenerate across subsequent molts, but regenerated limbs (uropods in particular) often stay visibly smaller than the original, and more severe injuries are more often fatal than not.

A blue coloration appearing in an otherwise normal-colored (usually gray) adult population can indicate a specific iridovirus infection that has, in the source material used for this guide, always proven fatal to the individual within a few months of the color change appearing. This is distinct from naturally occurring, healthy, heritable blue or purple color forms that exist in some species and lines — coloration alone isn't enough to tell the two apart. A previously normal-colored animal turning blue is the more concerning pattern than a line that has always displayed that color; if you're unsure, isolate the affected individual and watch for further changes rather than assuming either way.

Never release captive isopods, or discard used substrate outdoors, without sterilizing it first — this applies regardless of whether the species involved requires a permit, and is standard practice for any non-native invertebrate.

Difficulty

As a group, commonly kept isopods are frequently recommended as a beginner-friendly invertebrate, and many of the most widely available species — in genera such as Armadillidium, Porcellio, and Porcellionides, among others — are genuinely forgiving of imperfect conditions once established.

That said, isopods span a very wide range of care difficulty depending on species. Some need only a simple tub with occasional watering, while others — particularly some Mediterranean Porcellio species and a small number of specialty display species — require carefully managed ventilation, a deliberate dry/wet moisture gradient, or narrower temperature stability, and are better suited to keepers who already have some experience with the group. A few species referenced in the source material for this guide are difficult to keep reliably at all, even for experienced keepers, and are better treated as an advanced or experimental project than a standard recommendation.

If you're choosing a first species, favor ones commonly described as tolerant of a range of humidity and ventilation levels over ones flagged as needing a specific gradient or narrow temperature band — the general husbandry in this guide will get most beginner-friendly species through their first year without issue.

Frequently Asked Questions

Do I need a permit to own, buy, or move isopods?
It depends on what you're doing, not just what you own. Simply keeping isopods in a tub at home isn't the same regulatory question as importing them, breeding for sale, or shipping across state lines. In the United States, most non-native isopod species sold in the hobby require a PPQ 526 permit from USDA APHIS specifically to import, move across state lines, or release, though native species generally don't. Some states layer additional requirements on top of the federal rule. This is a real, currently enforced regulation, not just a formality — verify current requirements directly with APHIS and your state's department of agriculture before shipping or moving stock, since specifics can change.
My isopod looks pale or white — is it dead?
Not necessarily. If only half the body looks pale or a different texture, it's most likely mid-molt (isopods molt in two halves, a few days apart — see Health) and should even out within a day or two. If the whole animal is pale, it's more likely a young manca, a shed exoskeleton, or (in some species) a naturally pale or white color form. A genuinely dead animal is usually hollow-looking and motionless rather than simply light-colored.
Do I need to add calcium to my isopods' diet?
Calcium itself is essential to isopod biology — their exoskeleton is calcium-mineralized — but adding a separate calcium supplement on top of a normal diet is genuinely debated, including among current commercial and hobbyist sources, not just within this guide. Testing described in the primary source material for this guide found no consistent benefit from added calcium sources on top of good food, and well-fed cultures have thrived for many years without any, likely because isopods already recycle calcium through their diet, substrate, and their own shed exoskeleton — though other current sources argue supplementation helps prevent failed molts. Good-quality leaf litter appears to matter more than any specific calcium supplement either way, and offering a small calcium source as optional insurance is a reasonable middle ground given the disagreement.
Why isn't my isopod colony reproducing?
This is usually multi-causal rather than one single fix. Worth checking, roughly in order: whether the species needs a specific food (often aged leaf litter) as a reproductive trigger, whether temperature has been stable rather than fluctuating, and whether there's enough shelter for young to survive if adults are present. Day length or lighting is sometimes suggested as a factor for a few notoriously difficult species, but this isn't well established and shouldn't be assumed as the answer.
Can I collect isopods outdoors instead of buying them?
Yes, for common non-native (adventive) species, which are abundant under rocks, logs, and mulch in most yards. Only collect where you actually have permission and where local rules allow it, avoid protected habitats, and avoid native species specifically — collecting and using native species commercially raises separate regulatory questions from working with established non-native stock (see the permit question above). Be cautious about pesticide exposure at the collection site, and never release captive stock back outdoors afterward, including stock that started as wild-collected.
Are all isopods roughly the same to keep?
No — see Difficulty above. Many common species are genuinely easy, but some specialty and display species need more precise ventilation and moisture management, and a few are difficult even for experienced keepers.

Additional Resources