Armadillidium vulgare "St. Lucia" (Jelly Bean Isopods) is a Caribbean locale of the common pillbug, famous for producing remarkable colour variation within the same colony. Named after their resemblance to multicoloured jelly beans, individuals from a single colony can display colours ranging from deep burgundy to bright orange, yellow, grey, and everything between. This natural polymorphism has fascinated keepers and researchers alike—even breeding same-coloured parents together produces varied offspring. Beyond their visual appeal, they're confident, active isopods with excellent appetites, making them genuinely enjoyable to keep.
A Glimpse
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Origin: Saint Lucia Island, Caribbean
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Scientific Name: Armadillidium vulgare "St. Lucia"
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Maintenance required: Low
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Average Size: 1.5-2 cm (up to ¾ inch)
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Rarity: Low (widely available)
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Lifespan: 2-3 years
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Temperature: 21-27°C (70-80°F)
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Ventilation: Medium
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Humidity: 70-80%
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Favorite food: Leaf litter, vegetables, fruits, organic matter
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Supplements: Cuttlefish bone, calcium powder
Armadillidium vulgare St. Lucia: Introduction
Saint Lucia is a volcanic island in the eastern Caribbean known for its tropical climate and diverse ecosystems. The isopods from this locale have developed a striking polymorphic trait—dramatic colour variation that occurs naturally within populations regardless of selective breeding.
What makes Jelly Beans scientifically interesting is that this colour variation appears genetically fixed in a way that resists isolation. Researchers and hobbyists have attempted to breed single-colour lines by pairing same-coloured individuals, but offspring consistently display the full range of colour variation. This suggests complex genetic mechanisms controlling their colouration rather than simple inheritance patterns.
Beyond the science, they're simply enjoyable isopods to keep. The seller's personal observation captures their appeal well: "Jelly beans are one of my favourite isopods... they are very confident isopods with great appetites, they are often seen on top of the cork bark in the tub and unlike a lot of other isopods which wait until it's quiet or the lights go off before getting food you add to the tub, Jelly beans go for the food right away and eat it very quickly."
This bold, active behaviour makes them more visible and entertaining than shy, nocturnal species. Combined with their colour variation and straightforward care, they're genuinely rewarding to keep.
Armadillidium vulgare St. Lucia: Physical Traits and Characteristics
- Adults reach approximately 1.5-2 cm (up to ¾ inch)
- Segmented body covered in smooth, shiny exoskeleton
- Full conglobation ability (roll into tight, complete balls)
- Colour variation within colonies includes:
- Deep burgundy/maroon
- Bright orange
- Yellow
- Grey
- Various intermediate shades
- No two individuals look identical in mixed colonies
- Rounded, dome-shaped body typical of Armadillidium
- Pattern and colour intensity varies between individuals
The colour variation is the defining characteristic. A colony of Jelly Beans looks like a scattered handful of actual jelly bean sweets—each individual displaying different colouration.
Behaviour
Jelly Bean isopods display notably confident, engaging behaviour.
Activity patterns: Unlike many isopods that wait for darkness or quiet, Jelly Beans are bold and active. They're frequently visible on surfaces, exploring openly rather than hiding constantly. They respond to food immediately rather than waiting for nightfall.
Feeding behaviour: Excellent appetites with enthusiastic feeding response. They go for food right away when offered and eat quickly. This makes feeding them satisfying—you see immediate response rather than wondering if they've found the food.
Social behaviour: Highly social creatures that thrive in groups. They interact regularly with colony members and shouldn't be kept individually. Colonies display social hierarchy with dominant individuals.
Dominance behaviour: Dominant isopods exhibit "stacking"—positioning themselves above others to display status. This hierarchy behaviour is observable in established colonies.
Conglobation: Excellent rollers. When threatened, they curl into tight, complete balls—the classic pillbug defence that gives Armadillidium their common name.
Confidence: Generally bolder than many isopod species. They don't hide as extensively and become visible colony members rather than secretive substrate dwellers.
Diet
Jelly Bean isopods are detritivores with hearty, unfussy appetites.
Primary foods:
- Leaf litter (staple food source)
- Decaying organic matter
- Rotting hardwood
- Cork bark
Fruits (offered in moderation):
- Apples
- Berries
- Bananas
- Other soft fruits
Vegetables:
- Carrots
- Courgette (zucchini)
- Cucumber
- Sweet potato
- Leafy greens
Protein sources:
- Shrimp pellets
- Fish food flakes
- Dried shrimp
- Crushed high-quality pet food
Calcium sources:
- Cuttlefish bone (essential)
- Calcium powder supplements
- Crushed limestone
- Eggshells
Feeding approach: Their enthusiastic appetites mean they consume food quickly. Offer varied diet including protein and calcium-rich options alongside their leaf litter staple. Their bold feeding behaviour makes it easy to observe consumption and adjust portions accordingly. Remove uneaten fresh foods to prevent mould.
Armadillidium vulgare St. Lucia: Breeding
Jelly Beans breed readily and reliably in captivity.
Breeding rate: Fast. They reproduce quickly and colonies grow well under appropriate conditions. Prolific breeding is characteristic of the species.
Reproductive strategy: Females use brood pouching—carrying fertilised eggs in a marsupium (pouch) until offspring are ready to emerge. This provides protection during development and improves offspring survival rates. Fully formed juveniles emerge from the pouch ready to explore independently.
Breeding requirements:
- Appropriate humidity (70-80%)
- Stable warm temperatures
- Adequate calcium for gravid females
- Sufficient food supply
- Social group (they breed in colonies, not isolation)
Colour inheritance: Interestingly, breeding same-coloured individuals doesn't produce single-colour offspring. The colour variation appears to be maintained regardless of parental colouration—offspring display the full range of colours even when parents are identical. This makes "isolating" specific colours essentially impossible with current understanding.
Colony management: Their prolific breeding means colonies can grow substantially. Ensure enclosure size accommodates growing populations or be prepared to divide colonies.
Armadillidium vulgare St. Lucia: Habitat Setup
Creating appropriate conditions is straightforward given their adaptable nature.
Enclosure: Transparent containers or tanks work well—their colourful appearance deserves visibility. Ensure adequate space for colony movement and growth. Good ventilation is important but balance with humidity retention. Secure lids prevent escapes.
Substrate: Use moisture-retaining substrate soft enough for burrowing:
- Organic topsoil as a base (pesticide-free)
- Sphagnum peat moss mixed throughout
- Sphagnum moss patches for moisture retention
- Crushed limestone or calcium powder incorporated
- Leaf litter layered on top (serves as food and cover)
Substrate should be moist but not waterlogged. Overwetting causes mould and bacterial growth.
Humidity: 70-80%—they need consistent moisture reflecting their humid Caribbean origins:
- Maintain moist substrate throughout
- Mist regularly to maintain humidity
- Provide moisture gradient where possible
- Leaf litter helps retain humidity
- Balance moisture with ventilation to prevent stagnation
Ventilation: Medium ventilation. Adequate airflow prevents mould while maintaining humidity. Ventilation holes in enclosure sides work well.
Décor and hides:
- Driftwood pieces
- Cork bark and tubes
- Flat bark sections
- Leaf litter coverage
- Various hiding spots distributed throughout
These serve dual purposes—activity spaces for exploration and hiding spots for security. Their confident nature means they'll use open spaces as well as hides.
Temperature: 21-27°C (70-80°F). Room temperature in UK homes typically works. They appreciate gentle warmth—heat lamps can be beneficial but aren't essential in heated homes.
Lighting: They tolerate gentle light better than strictly nocturnal species. Their bold behaviour means they don't hide immediately when exposed to light. However, avoid harsh direct lighting or placement in bright sunlit locations.
Water: A shallow water dish with clean water can be provided. Alternatively, regular misting maintains hydration. Ensure any water dish has escape routes (pebbles or textured edges) to prevent drowning.
Bioactive Use
Jelly Bean isopods function well as bioactive cleanup crew with added visual interest.
Best suited for:
- Tropical bioactive enclosures
- Humid vivarium setups
- Display terrariums where colourful cleanup crew adds interest
- Planted tanks needing detritivores
- Any setup maintaining 70-80% humidity
Advantages:
- Multicoloured appearance adds genuine visual interest
- Bold behaviour makes them visible rather than hidden
- Prolific breeding maintains populations
- Enthusiastic feeders process waste effectively
- Hardy Armadillidium genetics
Considerations:
- Require higher humidity than some Armadillidium species
- Caribbean origins mean they prefer consistent warmth
- Prolific breeding can lead to large populations
Compared to other cleanup crew: More colourful than standard A. vulgare. More humidity-dependent than Mediterranean Armadillidium. Bolder and more visible than many Cubaris species. Good choice when you want cleanup crew that's actually visible and interesting.
Suitability
Jelly Bean isopods suit a wide range of keepers.
Excellent choice for:
- Beginners wanting attractive, easy isopods
- Keepers wanting visible, active species
- Anyone interested in colour variation genetics
- Humid bioactive setups needing colourful cleanup crew
- Display enclosures where appearance matters
- Those who find shy, hiding isopods frustrating
Not ideal for:
- Arid or low-humidity setups
- Keepers wanting to isolate single-colour lines (not possible)
- Very small enclosures (they need group living)
Care level: Low difficulty. They're hardy Armadillidium with straightforward requirements. Their bold nature and good appetites make them easy to monitor and feed. Prolific breeding means colonies establish readily. One of the easier species to keep successfully.
Value assessment: At £12 for 10, they offer excellent value for attractive, engaging isopods. The colour variation means every individual is visually interesting. Their confident behaviour and reliable breeding make them genuinely enjoyable rather than just functional. More visually appealing than standard A. vulgare at only modest price increase.
Expectations: Expect a colourful, active colony that's actually visible and entertaining to watch. Expect bold feeding behaviour that makes interaction satisfying. Expect prolific breeding that builds colonies quickly. Don't expect to isolate single colours—the variation is part of their charm. Expect hardy isopods that reward basic care with thriving, growing populations.
The appeal: Jelly Beans combine the hardiness of common Armadillidium vulgare with genuine visual interest and engaging behaviour. They're isopods you'll actually see and enjoy watching, not just functional decomposers hidden in substrate. For keepers wanting personality alongside practicality, they deliver on both fronts.
