Springtails and Isopods: The Clean-Up Crew Explained

What a clean-up crew does

On the forest floor, small animals break down dead leaves and other debris, returning nutrients to the soil. A terrarium is a tiny version of that system, and a clean-up crew helps keep it balanced. Springtails and isopods are the two most common members of the crew, and they do different jobs.

Springtails

Springtails are tiny, wingless hexapods, usually under 3 mm long. They are closely related to insects but are classed separately. They graze on mould, fungal growth and fine decaying matter on the substrate and glass. Springtails are often a sign of a working food web, since they show up in small numbers and are most visible when you lift the lid or tilt a leaf.

They are sensitive to drying out and to waterlogged, stagnant conditions. A jar with slightly damp surface soil suits them well.

Isopods

Isopods, often called woodlice or pill bugs, are small crustaceans. Species used in terrariums are typically a few millimetres to about a centimetre long. They chew through dead leaves, leaf litter and organic waste, breaking material into smaller pieces that springtails and microorganisms can process further.

Isopods need more food and steadier moisture than springtails. They do best in a deeper substrate with plenty of leaf litter, and very dry air can stress them.

How many to add

A starter tub from a reputable supplier is usually enough for a small closed terrarium. Adding too many clean-up animals at once can cause overcrowding and die-off, and the remains add to the waste you are trying to manage. Introduce them after planting and settling, once the substrate is damp and the plants are established.

Keeping the crew healthy

• Keep the substrate lightly damp, not soaked.
• Add a small piece of dead leaf now and then as food.
• Remove visible dead animals and heavy waste.
• Avoid cleaning sprays, perfumed products and pesticides inside the jar.
• Watch the population. A sudden drop often means the food has run out or the jar is too wet or too dry.

Clean-up crews are not a substitute for good build choices. If a jar has a constant mould problem, it usually needs less water, more airflow or a different plant mix. The crew tidies up what the system produces. It cannot fix a build that is out of balance.