{"product_id":"gestroi-isopods","title":"High Yellow Spotted Giant Isopods (Armadillidium Gestroi)","description":"\u003cp\u003eThe Armadillidium gestroi — commonly known as the Yellow Spotted Isopod — is one of the most visually striking Armadillidium species in the hobby. Acid-yellow spots scattered across a rich purple-grey to dark base body create a high-contrast pattern that genuinely stands out from any other isopod we stock. They're also among the largest Armadillidium species available, reaching up to 20 mm — noticeably bigger than the more common \u003ca href=\"\/products\/zebra-isopods\"\u003eZebra Isopods\u003c\/a\u003e and equally bold in temperament.\u003c\/p\u003e\n\u003cp\u003eNative to southern France and northern Italy, gestroi inhabit rocky cliffs and limestone outcrops in the Mediterranean — environments that shape their care requirements (drier than tropical species, calcium-rich, and well-ventilated). They're generally considered an excellent all-rounder: visually rewarding, hardy, and relatively easy to keep, though they grow and breed more slowly than prolific species.\u003c\/p\u003e\n\u003cp\u003eAvailable in groups of 5, 10, or 20. Captive-bred stock from established UK colonies. Mixed sizes included to establish a balanced colony with breeding potential.\u003c\/p\u003e\n\u003ch2\u003eQuick Care Summary\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eScientific Name:\u003c\/strong\u003e \u003cem\u003eArmadillidium gestroi\u003c\/em\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCommon Names:\u003c\/strong\u003e Yellow Spotted Isopod, High Yellow Spotted Isopod, Gestro's Pill Woodlouse\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFamily:\u003c\/strong\u003e Armadillidiidae\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOrigin:\u003c\/strong\u003e Southern France (Aquitaine region) and northern Italy — rocky cliffs and limestone outcrops\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAdult Size:\u003c\/strong\u003e Up to 20 mm — largest Armadillidium species\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLifespan:\u003c\/strong\u003e 1–2 years typical\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDifficulty:\u003c\/strong\u003e Easy to Medium — beginner-friendly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature:\u003c\/strong\u003e 21–26°C (room temperature in most UK homes)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHumidity:\u003c\/strong\u003e 50–70% — drier than tropical species, with moisture gradient\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVentilation:\u003c\/strong\u003e Medium — slightly less than other Armadillidium\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConglobation:\u003c\/strong\u003e Yes — rolls into a tight ball when disturbed\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBehaviour:\u003c\/strong\u003e Active, bold, often visible during the day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBreeding:\u003c\/strong\u003e Slow to moderate — patience required\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eWhat Makes Yellow Spotted Isopods Special\u003c\/h2\u003e\n\u003cp\u003eSeveral factors have made \u003cem\u003eA. gestroi\u003c\/em\u003e one of the most sought-after Armadillidium species:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe colouration is genuinely striking.\u003c\/strong\u003e The acid-yellow spots against the dark purple-grey body create a high-contrast pattern that's distinct from any other isopod in the UK hobby. Some individuals show colour variation from neon yellow to pumpkin orange spots, and the pattern intensifies as animals mature. The colours are thought to function as aposematic warning signals — possibly a defensive evolution similar to that seen in the related \u003ca href=\"\/collections\/armadillidium-isopods\"\u003eArmadillidium klugii (Clown Isopod)\u003c\/a\u003e.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAmong the largest Armadillidium.\u003c\/strong\u003e At up to 20 mm, gestroi are noticeably bigger than common Armadillidium species like \u003ca href=\"\/products\/zebra-isopods\"\u003eA. maculatum (Zebra)\u003c\/a\u003e. The size makes them substantial display animals — you can observe them from across the room rather than needing to peer closely.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eActive and observable.\u003c\/strong\u003e Gestroi are confident isopods that actively forage during the day as well as at night. They're not the kind of species that hides constantly — once established, you'll regularly see them out exploring the enclosure. This is a major advantage for display setups where you actually want to see your animals.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHard, calcified body.\u003c\/strong\u003e Their distinctly hardened exoskeletons contribute to their resilience. They handle minor husbandry mistakes that would stress softer-bodied species, and they're less prone to predation in mixed enclosures.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eConglobation.\u003c\/strong\u003e Like all Armadillidium, gestroi roll into a tight ball when disturbed. The conglobation behaviour combined with their striking colours makes them genuinely engaging to interact with — perfect for educational settings or for keepers who enjoy gently handling their isopods.\u003c\/p\u003e\n\u003ch2\u003eHow Yellow Spotted Isopods Compare to Other Armadillidium\u003c\/h2\u003e\n\u003cp\u003eIf you're choosing between Armadillidium species, here's how gestroi fit in:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003evs \u003ca href=\"\/products\/zebra-isopods\"\u003eZebra Isopods (A. maculatum)\u003c\/a\u003e:\u003c\/strong\u003e Both are popular display Armadillidium. Zebras have black-and-white striping; gestroi have yellow spots on dark bodies. Zebras breed faster and are more prolific; gestroi grow larger and are more visually unusual. Zebras are the better starter species; gestroi are a step up in distinctiveness.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003evs Tenerife White \u0026amp; Light Purple Isopods:\u003c\/strong\u003e Both are Armadillidium with subtle locale-based colouration. Gestroi are bolder and higher-contrast; Tenerife are more subtle and pastel. Different aesthetic preferences.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003evs Magic Potion \/ Klugii morphs:\u003c\/strong\u003e Klugii (Clown Isopods) and Magic Potion are designer-bred selectively for vivid colour. Gestroi are a natural species with naturally striking colouration. Both are visually impressive; gestroi have the appeal of being \"wild-coloured\" rather than selectively bred.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eBrowse the full \u003ca href=\"\/collections\/armadillidium-isopods\"\u003eArmadillidium collection\u003c\/a\u003e to compare all species.\u003c\/p\u003e\n\u003ch2\u003eSetting Up the Enclosure\u003c\/h2\u003e\n\u003cp\u003eGiven gestroi's larger size, start with a slightly bigger enclosure than you'd use for smaller Armadillidium species. A shoebox-sized container or 15–20 litre tub suits a starter colony of 10. For breeding colonies, a 20×24 cm (8×10 inch) gasket-type tote or glass aquarium provides better long-term housing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eImportant:\u003c\/strong\u003e Mature male gestroi can be territorial. Provide multiple cork bark hides, rotting wood pieces, and egg crate sections to give males their own territories and minimise conflict. A single cramped enclosure with too many adult males will see fighting and stress.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eVentilation note:\u003c\/strong\u003e Where most Armadillidium need medium to high ventilation, gestroi prefer slightly less. They need airflow, but they don't tolerate the dry conditions that come with extensive ventilation. Add fewer ventilation holes than you would for Zebra Isopods or other Mediterranean species. Cross-ventilation through small holes on opposite sides works better than wide mesh sections.\u003c\/p\u003e\n\u003cp\u003eOur \u003ca href=\"\/collections\/accessories\"\u003eaccessories collection\u003c\/a\u003e has appropriate enclosures and small-vent options for gestroi setups.\u003c\/p\u003e\n\u003ch2\u003eThe Moisture Gradient\u003c\/h2\u003e\n\u003cp\u003eGestroi prefer a slightly more moist environment than most Armadillidium, but still need a moisture gradient rather than uniform dampness:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eOne-third moist:\u003c\/strong\u003e Sphagnum moss patches and damp leaf litter. Mist regularly to maintain. You'll often find individuals tucked into the moss pile.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMiddle zone:\u003c\/strong\u003e Moderately damp substrate with leaf litter cover\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDrier side:\u003c\/strong\u003e Drier substrate where they can choose drier conditions if needed\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eCork bark hides naturally create dry pockets underneath them, contributing to gradient variation without requiring careful zone management. Add multiple cork pieces throughout the enclosure for hides, breeding sites, and microclimate variation.\u003c\/p\u003e\n\u003ch2\u003eSubstrate\u003c\/h2\u003e\n\u003cp\u003eUse organic topsoil (pesticide-free) as a base, with at least 5 cm depth. Mix in \u003ca href=\"\/products\/flake-soil-1l\"\u003eflake soil\u003c\/a\u003e for added nutrition. Gestroi don't burrow as deeply as some species, but enough depth gives them options for moulting and security.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eLimestone is genuinely important.\u003c\/strong\u003e Their natural rocky cliff habitat is calcium-rich, and gestroi benefit from limestone access throughout the enclosure rather than just placed on top. Mix \u003ca href=\"\/products\/malawi-light-limestone-for-isopods\"\u003ecrushed limestone\u003c\/a\u003e into the substrate, and add a few visible pieces as habitat enrichment that mimics their wild environment.\u003c\/p\u003e\n\u003cp\u003eTop with generous leaf litter — \u003ca href=\"\/products\/large-magnolia-leaves-for-isopods\"\u003emagnolia leaves\u003c\/a\u003e for long-lasting cover and \u003ca href=\"\/products\/bamboo-leaf-litter\"\u003ebamboo leaf litter\u003c\/a\u003e for structure. Add cork bark pieces in multiple sizes for hiding and territory establishment.\u003c\/p\u003e\n\u003ch2\u003eTemperature\u003c\/h2\u003e\n\u003cp\u003e21–26°C is the comfort range, with stable conditions matter more than hitting any specific point. Most UK homes provide acceptable temperatures during warmer months; in winter, a low-wattage heat mat on the side of the enclosure (never underneath) connected to a thermostat keeps the colony stable.\u003c\/p\u003e\n\u003cp\u003eDaytime highs shouldn't exceed 28°C, and a small night drop (no lower than 18°C) is acceptable and may even be beneficial. Sustained exposure outside this range causes stress.\u003c\/p\u003e\n\u003ch2\u003eDiet\u003c\/h2\u003e\n\u003cp\u003eGestroi are detritivores with broad appetites and benefit from varied feeding:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrimary diet:\u003c\/strong\u003e Decaying leaf litter and rotting white wood — always available\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVegetables:\u003c\/strong\u003e Cucumber, courgette, sweet potato, carrot, butternut squash, pumpkin, mushrooms. Replace within 24–48 hours.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFruit (occasionally):\u003c\/strong\u003e Apple, banana, melon\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProtein (1–2x weekly):\u003c\/strong\u003e Essential. Options include \u003ca href=\"\/products\/dried-daphnia-100g\"\u003edried daphnia\u003c\/a\u003e, \u003ca href=\"\/products\/dried-silkworm-pupae-100g\"\u003esilkworm pupae\u003c\/a\u003e, \u003ca href=\"\/products\/ultra-tropical-fish-flakes-100g\"\u003efish flakes\u003c\/a\u003e, or \u003ca href=\"\/products\/freeze-dried-peas\"\u003efreeze-dried peas\u003c\/a\u003e. Place protein on the dry side of the enclosure.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCalcium (essential — non-negotiable for gestroi):\u003c\/strong\u003e Their rocky cliff origins mean they expect calcium-rich substrate. \u003ca href=\"\/products\/cuttlebone-100g\"\u003eCuttlebone\u003c\/a\u003e always available, plus \u003ca href=\"\/products\/malawi-light-limestone-for-isopods\"\u003elimestone\u003c\/a\u003e mixed throughout the substrate.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRepashy supplements:\u003c\/strong\u003e \u003ca href=\"\/products\/repashy-morning-wood\"\u003eMorning Wood\u003c\/a\u003e works well as a calcium-fortified regular supplement.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003ePlant-eating warning:\u003c\/strong\u003e Like most Armadillidium, gestroi may snack on soft live plants and moss in bioactive vivariums. Hardy plants and tough mosses fare better than ferns and softer species.\u003c\/p\u003e\n\u003ch2\u003eBreeding\u003c\/h2\u003e\n\u003cp\u003eGestroi are slower breeders than most Armadillidium — this is the main thing keepers need to know up front. Set realistic expectations.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eEstablishment timeline:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eJuvenile colonies often take 6+ months to reach full size\u003c\/li\u003e\n\u003cli\u003eSub-adults may begin breeding before reaching full adult size\u003c\/li\u003e\n\u003cli\u003eOnce established, broods are reasonably large but production is slower than fast-breeding species\u003c\/li\u003e\n\u003cli\u003eReproduction rates are noticeably lower than Zebra Isopods or other prolific Armadillidium\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eReproduction biology:\u003c\/strong\u003e Like all isopods, female gestroi carry developing eggs in a brood pouch (marsupium) on the underside of their body until juveniles emerge as live mancae. The \"brood pouch breeding\" approach protects offspring during development.\u003c\/p\u003e\n\u003cp\u003eFor successful breeding, maintain a balanced male-to-female ratio (excess males cause territorial conflict), provide ample hiding spots, ensure consistent calcium availability, and keep the moisture and temperature stable. Patience is the main requirement — don't expect explosive population growth even under perfect conditions.\u003c\/p\u003e\n\u003ch2\u003ePair With Springtails\u003c\/h2\u003e\n\u003cp\u003eAdd a thriving \u003ca href=\"\/collections\/springtails-for-sale\"\u003espringtail culture\u003c\/a\u003e to any gestroi setup. Springtails handle mould and microbial growth at a scale isopods can't manage. They coexist peacefully with gestroi and are essential rather than optional for any humid enclosure.\u003c\/p\u003e\n\u003ch2\u003eWhy Choose Yellow Spotted Isopods?\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eGenuine display value.\u003c\/strong\u003e Unlike many isopods that are functional but plain, gestroi offer real visual interest. The high-contrast yellow-on-dark patterning is distinctive enough to be the centrepiece of an enclosure rather than just inhabitants.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSize matters.\u003c\/strong\u003e At up to 20 mm, gestroi are large enough to genuinely observe and appreciate. Smaller species require closer inspection; gestroi are visible from across a room.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eActive during the day.\u003c\/strong\u003e Most isopods are nocturnal and rarely seen. Gestroi are confident and active during daylight hours, especially once colonies establish. This makes them genuinely viable as display animals.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eEducational appeal.\u003c\/strong\u003e The conglobation behaviour, large size, and bold colouration make gestroi excellent for classroom or family settings where children can observe and gently handle them.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHardy enough for beginners.\u003c\/strong\u003e Despite their visual impact, gestroi are forgiving of minor husbandry mistakes. Their hard exoskeletons and Mediterranean adaptation give them resilience that more delicate species lack.\u003c\/p\u003e\n\u003ch2\u003eRealistic Expectations\u003c\/h2\u003e\n\u003cp\u003eA starter colony of juveniles will take 6+ months before showing significant growth or beginning to breed. This isn't a fast-breeding species like Dairy Cows or Zebra Isopods — it's a slower, more methodical colony builder. If you want quick visible results, gestroi may frustrate you. If you want a long-term colony with striking visual impact and steady (if slow) growth, they reward the wait.\u003c\/p\u003e\n\u003cp\u003eNewly arrived specimens may also look less impressive than mature adults. Colour and pattern intensify with age and good nutrition. Given 2–3 months of stable conditions, juveniles develop into the bold, high-contrast adults you see in marketing photos.\u003c\/p\u003e\n\u003ch2\u003eBioactive and Mixed Setup Considerations\u003c\/h2\u003e\n\u003cp\u003eGestroi are slow growing and slow breeding, which means they're not ideal for amphibian or reptile vivariums where predation pressure could deplete the colony faster than it reproduces. They're better kept as standalone display colonies where the slow reproduction isn't a problem.\u003c\/p\u003e\n\u003cp\u003eFor planted setups, be aware of their plant-nibbling tendency. Hardy plants and tough mosses are fine; delicate ferns and soft mosses may suffer.\u003c\/p\u003e\n\u003ch2\u003eBuilding Your Setup — Pairs Well With\u003c\/h2\u003e\n\u003cp\u003eFor a complete Yellow Spotted Isopod setup:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/flake-soil-1l\"\u003e\u003cstrong\u003eFlake Soil\u003c\/strong\u003e\u003c\/a\u003e — fermented hardwood substrate for nutrition\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/large-magnolia-leaves-for-isopods\"\u003e\u003cstrong\u003eMagnolia Leaves\u003c\/strong\u003e\u003c\/a\u003e — long-lasting primary leaf litter\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/bamboo-leaf-litter\"\u003e\u003cstrong\u003eBamboo Leaf Litter\u003c\/strong\u003e\u003c\/a\u003e — structural leaf cover\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/cuttlebone-100g\"\u003e\u003cstrong\u003eCuttlebone\u003c\/strong\u003e\u003c\/a\u003e — essential calcium for moulting\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/malawi-light-limestone-for-isopods\"\u003e\u003cstrong\u003eMalawi Limestone\u003c\/strong\u003e\u003c\/a\u003e — essential for limestone-cliff origin species; mix into substrate generously\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/dried-daphnia-100g\"\u003e\u003cstrong\u003eDried Daphnia\u003c\/strong\u003e\u003c\/a\u003e — protein supplementation\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/freeze-dried-peas\"\u003e\u003cstrong\u003eFreeze-Dried Peas\u003c\/strong\u003e\u003c\/a\u003e — plant-based protein\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/dried-silkworm-pupae-100g\"\u003e\u003cstrong\u003eDried Silkworm Pupae\u003c\/strong\u003e\u003c\/a\u003e — high-fat treat for breeding conditioning\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/ultra-tropical-fish-flakes-100g\"\u003e\u003cstrong\u003eUltra Tropical Fish Flakes\u003c\/strong\u003e\u003c\/a\u003e — formulated insect-based protein\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/repashy-morning-wood\"\u003e\u003cstrong\u003eRepashy Morning Wood\u003c\/strong\u003e\u003c\/a\u003e — calcium-fortified gel premix\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/springtails-for-sale\"\u003e\u003cstrong\u003eSpringtails\u003c\/strong\u003e\u003c\/a\u003e — bioactive cleanup crew\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/accessories\"\u003e\u003cstrong\u003eEnclosures \u0026amp; Air Vents\u003c\/strong\u003e\u003c\/a\u003e — properly ventilated housing with good seal\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eFor a deeper guide to this species, read our blog post on \u003ca href=\"\/blogs\/isopods-useful-articles\/gestroi-isopod-care\"\u003eArmadillidium gestroi care\u003c\/a\u003e. Browse the full \u003ca href=\"\/collections\/armadillidium-isopods\"\u003eArmadillidium collection\u003c\/a\u003e for related species and morphs, or explore \u003ca href=\"\/collections\/isopods-for-sale\"\u003eall isopods\u003c\/a\u003e for the complete catalogue.\u003c\/p\u003e","brand":"PostPods","offers":[{"title":"10","offer_id":45085313302822,"sku":"AHY10","price":15.0,"currency_code":"GBP","in_stock":true},{"title":"20","offer_id":45085313335590,"sku":"AHY20","price":27.5,"currency_code":"GBP","in_stock":true},{"title":"100","offer_id":45173008302374,"sku":"AHY100","price":110.0,"currency_code":"GBP","in_stock":true},{"title":"50","offer_id":45173008335142,"sku":"AHY50","price":60.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0759\/0707\/2294\/files\/high-yellow-spotted-giant-isopods-armadillidium-gestroi-103055.jpg?v=1750256682","url":"https:\/\/postpods.co.uk\/products\/gestroi-isopods","provider":"Isopods For Sale UK | PostPods","version":"1.0","type":"link"}