isopods

What is an isopod?

An isopod is a terrestrial crustacean, commonly known as a woodlouse or pill bug, although not every species can roll into a ball. There are more than 10,000 species of isopod. Unlike insects, whose exoskeleton is made of chitin, isopods are covered in calcium carbonate, which also makes them a natural source of minerals for reptiles and amphibians.

People keep isopods for two reasons. The first is as collectable pets: there are rare species with very striking colours, and it is rewarding to watch the colony grow and new colour forms appear. The second is as a clean-up crew for bioactive terrariums, because they are decomposers: they eat leftover food, dead insects, shed skin and even droppings, keeping the substrate clean and aerated. This collection includes species from the genera Cubaris, Porcellio, Armadillidium and Porcellionides, as well as other genera that are less common.

What do isopods eat?

Isopods eat decaying organic matter, and the basis of their diet is dry leaves, which also give them somewhere to hide. Their favourites are walnut, mulberry, oak, cherry, rose, bramble and chestnut leaves. With a generous layer of leaves, the colony never runs out of food.

As a supplement they accept vegetables or peelings, especially carrot, and fruit such as apple or pear. In our breeding they always have a lid with dry food: tropical fish food, gammarus for turtles, dog food, seeds, rabbit food or wheat bran, or a food for isopods and springtails. Calcium is essential, so there should always be a cuttlefish bone available. Food is placed in a dish so it does not touch the substrate, which stops it going mouldy.

How do you set up an isopod terrarium?

The simplest isopod terrarium is a ventilated plastic box with about three fingers' depth of substrate. It is the same system we use in our facilities to keep and breed most species, with stackable boxes that let you keep several species in little space.

• Substrate: 50% coconut fibre, 40% multi-purpose compost, 5% vermiculite and 5% garden soil, mixed with dried leaves, rotting wood and reptile sheds.
• Surface: plenty of dried leaves, a cuttlefish bone and a feeding dish.
• Hides: cork bark, half a coconut shell, egg cartons or moss.
• Humidity: one more humid area and one drier area; tropical species, such as some Cubaris, need 80-90% and 24-27 °C.

The isopod breeding terrarium kit includes the box and the ready-made substrate.

Which isopods should you choose to start with?

To start with, the best isopods are the genera Porcellionides, Porcellio laevis and Armadillidium: they are hardy, easy to keep and affordable. The choice depends on what you want them for:

• Cleaning bioactive terrariums: Porcellionides pruinosus and Porcellio laevis, which are very prolific, so they form self-sustaining colonies that also serve as calcium-rich live food.
• True pill bugs: Armadillidium, such as Armadillidium granulatum «naranjito» or Armadillidium vulgare «magic potion», which roll up into a ball when they feel threatened.
• Collecting: Cubaris, such as the «panda king» or «rubber ducky» varieties, and rare genera such as Ardentiella or Merulanella. Many of these species breed more slowly and are kept mainly as pets.
• Large size: Porcellio expansus, one of the most impressive isopods, with a flattened body and contrasting colours.

How do isopods reproduce?

Isopods reproduce sexually. After mating, the female carries the eggs and embryos in the marsupium, a pouch under the body that protects the young from drying out and provides them with nutrients and antibacterial elements. When the young are ready, the mother releases them fully formed: they look very much like the adults, only small.

Within a few months those young can breed themselves, so a well-kept colony grows on its own. For that to happen, the box needs a good layer of dry leaves, calcium always available and stable humidity. The rate varies greatly between species: Porcellionides pruinosus and Porcellio laevis are very prolific, whereas some collector Cubaris, such as ‘jupiter’, are slow. All the details are in our guide to keeping and breeding isopods.