---
title: Dairy cow isopod in a terrarium | Glass Jar Garden
description: Dairy cow isopod (Porcellio laevis): A big, fast, hungry isopod. Strips litter quickly and nibbles soft plants. Needs eats litter 1.5 mg/day each, eats mould...
url: https://glassjar.garden/guide/critters/porcellio-laevis/
---

Critters

# Dairy cow isopod
Porcellio laevis

Open jar only · Grazes plants

A big, fast, hungry isopod. Strips litter quickly and nibbles soft plants.

## What the simulation uses

- Eats litter: 1.5 mg/day each (Dead leaves one animal shreds a day, turning them back into soil.)

- Eats mould: 0.2 mg/day each (Mould one animal grazes a day, keeping fuzz and grey mould down.)

- Colony at most: 400 per m² (How many the floor can feed when food is plentiful; less food, fewer.)

- Starving loses: 2 % a day (How fast a colony thins when the jar cannot feed it.)

- Eats: decaying plant, leaf litter, rotting wood, moss, lichen, animal waste, fungi (Foods it lives on; the jar feeds it from whichever of these it has.)

- Humidity: 55 to 85 % RH (Air moisture it needs.)

- Temperature: 18 to 30 °C (Comfortable range; beyond it the colony suffers.)

- Doubles in: 45 days (Time for the colony to double with plenty of food.)

- Lives: 912.5 days (How long one animal lives.)

## Care

- Size: 12 to 20 mm

- Moisture: Moist

## What kills it

- complete drying
- stagnant saturated substrate
- overcrowding with no food (cannibalism)

## Description
Growing up to 2 cm, it eats heavily and will chew moss as well as soft plants. It belongs in a big or lightly planted enclosure rather than a small closed jar. Keep food on hand, because hungry, crowded colonies turn on each other.

Also called dairy cow, swift woodlouse, smooth slater.

Estimated, where sources were thin: clutch_or_offspring; maturity_days; generation_days; lifespan_days; temp_c; humidity_rh_pct.

## Sources

- [en.wikipedia.org/wiki/Porcellio_laevis](https://en.wikipedia.org/wiki/Porcellio_laevis)
- [en.wikipedia.org/wiki/Woodlouse](https://en.wikipedia.org/wiki/Woodlouse)

[Grow it in a jar](https://glassjar.garden/?guide=critters/porcellio-laevis)

[Common rough woodlouse](https://glassjar.garden/guide/critters/porcellio-scaber/) · [Dwarf white isopod](https://glassjar.garden/guide/critters/trichorhina-tomentosa/) · [All critters](https://glassjar.garden/guide/critters/)