Porcellio expansus
A large, charismatic Iberian species with a growing following in the hobby.
About this species
Porcellio expansus is a large isopod native to the Iberian Peninsula. Adults are broad-bodied and impressive in size, making them popular display animals. The species has gained a steady following among collectors who appreciate larger Porcellio species.
Like all isopods, P. expansus is a terrestrial crustacean — not an insect — that breathes through gill-like pleopods on its underside. As a Porcellio, it cannot conglobate (roll into a ball). It originates from a Mediterranean climate and appreciates moderate, well-ventilated conditions.
Enclosure
Given its size, a tub with at least a 30x20 cm footprint is recommended for a starter colony. Good ventilation is important — P. expansus does not tolerate stagnant, overly humid conditions. Furnish with cork bark, dried leaves, and cuttlebone. Egg cartons provide additional surface area and hiding spots.
Substrate
- 60% coco coir
- 20% organic topsoil
- 10% sand for drainage
- 10% crushed hardwood leaf litter
Maintain a moisture gradient. P. expansus prefers moderate humidity — not as dry as some Armadillidium, not as wet as tropical species. Depth 6–10 cm to allow burrowing. Top with dried oak or beech leaves. Never use softwood (pine, cedar) — toxic to all isopods.
Feeding
- Dried hardwood leaves — staple food
- Vegetables: courgette, carrot, sweet potato
- Cuttlefish bone — essential for calcium and exoskeleton mineralisation
- Protein once or twice weekly: dried shrimp, fish flakes, or dried insects
Larger species consume more food proportionally. Ensure adequate protein to prevent stress behaviours in dense colonies. Remove fresh food within 48 hours.
Breeding
P. expansus breeds at a moderate pace. Females carry eggs in a marsupium and produce decent-sized broods. Colony growth is steady — not as explosive as P. laevis or P. dilatatus, but reliable. Starting with 15 or more individuals is recommended to ensure a viable breeding population.