Guide
Springtails vs isopods
Each crew is a colony that grows to what the jar can feed. Springtails are the mould eaters: tiny, fast-breeding, and happiest in wet soil. Isopods are the litter eaters: bigger, slower, and better in drier jars, though hungry ones nibble soft plants.
| Critter | Eats | Humidity | Doubles in | Jar |
|---|---|---|---|---|
| Common pill bug | decaying plant, leaf litter, fungi, animal waste, dead animals, seeds, seedlings | 60 to 90 % RH | 90 days | Fine in a closed jar, Grazes plants |
| Common rough woodlouse | decaying plant, leaf litter, rotting wood, fungi, bacteria biofilm, frass | 50 to 85 % RH | 67.5 days | Fine in a closed jar, Grazes plants |
| Dairy cow isopod | decaying plant, leaf litter, rotting wood, moss, lichen, animal waste, fungi | 55 to 85 % RH | 45 days | Open jar only, Grazes plants |
| Dwarf white isopod | decaying plant, leaf litter, frass, mould, fungi, animal waste | 80 to 100 % RH | 45 days | Closed jar only |
| Little sea isopod | decaying plant, leaf litter, rotting wood, fungi, frass, animal waste | 70 to 95 % RH | 90 days | Closed jar only, Grazes plants |
| Miniature awlsnail | decaying plant, biofilm, algae, fungi, calcium sources | 80 to 100 % RH | 67.5 days | Closed jar only, Grazes plants |
| Powder orange / powder blue isopod | decaying plant, leaf litter, rotting wood, frass, fungi, animal waste, fish food protein | 60 to 90 % RH | 45 days | Fine in a closed jar, Grazes plants |
| Silver springtail | mould, fungi, biofilm, decaying plant, frass | 80 to 100 % RH | 15.5 days | Closed jar only |
| Temperate white springtail | mould, fungi, fungal hyphae, biofilm, decaying plant, yeast | 90 to 100 % RH | 10.5 days | Closed jar only |
| White worm / potworm | decaying plant, microbes, fungi, frass, leftover food | 90 to 100 % RH | 30 days | Closed jar only |
How the simulator runs the crew
- Each eats what its diet lists: leaves, rotting soil matter, fungi, rotting wood, moss or algae.
- Colonies grow toward the jar's food, then hold there.
- Short of food, a colony thins out over weeks.
- Springtails crash in dry soil; isopods cope better.
- Hungry isopods nibble soft plants.
Which to add
- Any sealed jar: springtails, for the mould.
- A jar with leaf litter or wood: add a few small isopods too.
- A jar of soft seedlings: springtails only, or few isopods.
More terrarium guides
- Closed vs open terrariumWhich to build, and which plants suit each.
- Best plants for a closed terrariumPlants that live sealed, easiest first.
- Best moss for a terrariumMosses for closed and open jars, and what they grow on.
- Terrarium layers explainedDrainage, barrier, soil and top dressing, and what each does.
- Terrarium drainage: LECA vs gravel vs lava rockEvery drainage material side by side.
- Mould in a terrariumWhy new jars fuzz, which mould matters, and how to stop it.