The Porcellio laevis 'Dairy Cow' is a popular and striking color morph of the common swift woodlouse or pill bug (Porcellio laevis). Named for its distinct black and white, cow-like patterning, it is highly valued in the invertebrate hobby due to its hardiness, active nature, and rapid breeding.
 
Key Characteristics
Appearance: They are large for a typical isopod, reaching up to 2 cm (0.8 inches) in length. Their dorsal surface is smooth, and they feature a bold, irregular pattern of black splotches on a white or pale background.
Behavior: Unlike some shy species, 'Dairy Cows' are known for being bold and active, often staying on the surface of the substrate even during the day. When disturbed, they can move with surprising speed.
Role: Their voracious appetites make them excellent members of a bioactive clean-up crew in terrariums, where they break down organic matter efficiently. 
 
Husbandry and Care
P. laevis 'Dairy Cow' are considered one of the best beginner species because they are very tolerant of a wide range of conditions. 
Habitat: They require an enclosure with good cross-ventilation and a moisture gradient, featuring both a damp area (maintained with sphagnum moss) and a drier side.
Substrate & Hides: A deep substrate layer of organic soil, decaying leaf litter, and rotting white wood is essential. They enjoy hiding under pieces of cork bark or magnolia leaves.
Temperature & Humidity: They thrive in standard room temperatures, roughly 20–26°C (68–79°F), and moderate humidity.
Diet: As detritivores, their primary food source is decaying organic matter. They have high protein and calcium requirements:
Protein: Supplement regularly with high-protein sources like fish flakes, dried shrimp, or freeze-dried minnows to prevent them from potentially nibbling on soft-bodied tank inhabitants.
Calcium: A constant supply of calcium through cuttlebone, eggshells, or limestone is vital for their large, robust exoskeletons.
Breeding: They are extremely prolific breeders and will establish a large colony quickly under optimal conditions.