Isopods
Not one of these is an insect and not one of them can hurt you. Woodlice, pill bugs and the terrarium species people pay a lot of money for are all crustaceans that never went back to the sea.
5 species, each checked against a reference source.
All species
Start with a photograph
Identify this bug from a photo. The result includes confidence, common lookalikes and a plain safety assessment; read its accuracy and limits before treating a low-evidence photo as definitive.
How to know you have an isopod
They get called bugs, beetles and even baby armadillos, and none of those is close. The body plan is distinctive once you know what to count.
- Seven pairs of legs. An insect has three pairs, a spider four.
- Overlapping armoured plates across the back, like segmented banding.
- Two obvious antennae held forward, and no wings at any stage.
- Found in damp — under stones, logs, pots and leaf litter, never in dry open ground.
- Rolls into a complete ball? Pill bug. Flattens and runs? Sow bug.
Indoors, they are a symptom rather than a problem
Isopods breathe through structures that have to stay wet, which means they cannot survive long in a heated room and cannot establish a population in one. Every woodlouse you find indoors walked in and is dying. That makes them genuinely useful: repeated appearances in the same spot point at moisture getting in there, and treating the animals achieves nothing while the damp remains. Nobody needs to spray for woodlice.
Common questions
Are isopods insects?
No. They are crustaceans, more closely related to crabs and shrimp than to anything with six legs, and they still breathe through gill-like structures.
Do woodlice or pill bugs bite?
Neither. They have no biting mouthparts of any consequence, no venom and no sting, and they are safe for children to pick up.
Why would anyone keep them?
They clean up. In a bioactive terrarium they eat mould, waste and decaying leaf litter so the enclosure does not need stripping out. Some species are also genuinely beautiful, which is how the hobby prices got where they are.
Are they damaging my plants?
Very rarely. They prefer decaying material, and damage to living plants usually means there is nothing dead left for them to eat.