Armadillidium granulatum is one of the more accessible Mediterranean Armadillidium species - large, hardy, and available in several attractive morphs. This guide covers honest care requirements based on their actual biology and typical hobby practice in the UK. For an alternative perspective see our companion article granulatum isopod care.
About the Species
Armadillidium granulatum is a Mediterranean species native to southern Europe - Italy, Sicily, Sardinia, and surrounding regions. NOT tropical despite occasional misclassification. Their natural habitat is dry Mediterranean scrubland and limestone-rich substrates, which informs everything about how to keep them.
Key biological points:
- Size: 15-18mm adults - one of the larger Armadillidium species
- Origin: Mediterranean (southern Europe, including limestone-rich islands)
- Behaviour: Conglobators (roll into a ball when disturbed)
- Reproduction: Sexual, not parthenogenetic. Males and females both required for breeding. Live young carried in marsupium (brood pouch)
- Gestation: Approximately 30 days
- Breeding rate: Moderate - slower than P. scaber or P. laevis but reliable in good conditions
- Lifespan: 2-3 years for adults
Available Morphs
Several selectively-bred colour morphs are available in the UK hobby:
- High Yellow - distinctive yellow spots on dark grey base. The most popular morph. Browse our A. granulatum High Yellow
- Orange - overall orange-tinted body. Browse our A. granulatum Orange
- Pearl - pearlescent white-cream colouration. Browse our A. granulatum Pearl
- Standard wild type - grey base with subtle markings. Browse our A. granulatum
Enclosure Setup
Container
10-litre minimum for a starter colony. Larger is better for breeding success. Plastic storage containers with secure lids work well - add ample ventilation.
Substrate
Standard Mediterranean Armadillidium substrate mix:
- 40-50% coconut fibre (coir) as moisture-retaining base
- 20-30% organic topsoil or flake soil - our flake soil
- Crumbled decaying hardwood throughout - our shredded rotten wood
- Generous leaf litter on top - our leaf litter
- Small limestone pieces scattered through (their natural Mediterranean substrate)
Depth: 5-8cm minimum. Avoid peat moss (acidic, wrong for Mediterranean species which prefer neutral-to-alkaline).
Ventilation
Important. Mediterranean species need good air movement - they don't tolerate the high humidity stagnation that suits tropical species. Use mesh ventilation panels for cross-flow. Our screw-in air vents.
Hides and Structure
- Cork bark - essential
- Lotus pods - natural enclosed spaces
- Decaying wood pieces (also food)
- Limestone pieces optional aesthetic plus calcium
Calcium
Always-available cuttlebone on substrate - never crushed or powdered. Passive access; isopods consume as needed. See our calcium supplementation article.
Environmental Conditions
Temperature
18-22°C - standard UK room temperature is fine. Don't need supplemental heating in most UK homes. Mediterranean species evolved with seasonal temperature variation and tolerate moderate ranges well. Heat mats or lamps are unnecessary and can actually stress them.
If your home is consistently cool (under 16°C in winter), a low-wattage heat mat under part of the enclosure provides a thermal gradient. Never heat lamps for isopods.
Humidity
60-70% with a humidity gradient. Mediterranean species need DRIER conditions than tropical Cubaris or Ardentiella. Both ends of the enclosure should differ:
- Wetter end: lightly misted substrate, sphagnum moss patches
- Drier end: rarely misted, more open substrate, closer to natural Mediterranean conditions
Mist the wetter end every few days; let the drier end mostly stay drier. This allows the colony to self-regulate - a critical Mediterranean species adaptation.
Feeding
Foundation Diet
- Leaf litter - the dietary foundation. Oak, beech, hornbeam, maple - see our leaves article
- Decaying hardwood - both food and habitat
- Flake soil - background nutrition
- Calcium - always-available cuttlebone
Fresh Vegetables (1-2 times weekly)
- Courgette/zucchini
- Carrot
- Cucumber
- Sweet potato
- Butternut squash
- Apple slices (occasionally)
Protein Supplements (Weekly Maximum)
Use established hobby options:
- Fish flakes - the standard. See our fish flakes article
- Dried shrimp / bloodworm - clean and easy. See our shrimp article
- Repashy Bug Burger - commercial isopod formulation
Avoid: cooked chicken or fish (attract mites and mould rapidly), excessive protein supplementation. For broader feeding context see our protein feeding article.
Breeding
A. granulatum is sexually reproducing. Both males and females required for breeding - there's no parthenogenesis in this species (despite some sources claiming otherwise).
Once mated, females carry developing embryos in their marsupium (brood pouch) for approximately 30 days before releasing live mancae (baby isopods). With proper husbandry, colonies produce broods regularly.
Breeding conditions:
- Stable temperature (18-22°C)
- Proper humidity gradient (drier end available)
- Adequate hides and refuges (especially important for vulnerable freshly-moulted individuals)
- Varied diet with adequate protein
- Consistent calcium provision
- Avoid frequent disturbance during breeding phases
Mancae develop within the substrate and emerge gradually. Don't worry if you don't see them immediately - they hide in substrate while small.
Common Mistakes
Treating as Tropical Species
The most common mistake. Keepers used to Cubaris husbandry maintain A. granulatum at tropical conditions - too humid, too warm. This stresses them and reduces breeding success.
Sealed Enclosures
Mediterranean species need ventilation. Sealed containers cause respiratory stress and colony decline.
Inadequate Calcium
Calcium dusting (sprinkling powder) doesn't work for isopods. Always-available cuttlebone is the proper hobby method.
Heat Lamps
Heat lamps dry out the enclosure and stress isopods. Never use them. Heat mats on thermostats only if needed for cool homes.
Over-Misting
Mediterranean species don't want soggy substrate. Light misting at one end, drier conditions at the other.
Their Place in a Collection
A. granulatum is an excellent intermediate species:
- Larger and more visually striking than basic UK natives
- Less demanding than premium Cubaris
- Multiple morph options available
- Reliable breeders with proper husbandry
- Conglobate display behaviour adds interest
Best started after basic species (Powder Orange, Dairy Cow, P. scaber morphs) have given you husbandry experience. Their slightly more specific needs (humidity gradient, ventilation) make them a useful intermediate stepping stone.
Companion Articles
For broader Armadillidium guidance see our Armadillidium collection. For setup essentials browse our accessories collection. For comprehensive setup guidance see our first isopods guide. For temperature considerations see our cold tolerance article.
For current stock browse our isopods collection.
Straightforward to keep once you understand they're Mediterranean species, not tropical. Get the humidity gradient and ventilation right and they'll thrive for years.
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