Ant HabitatsChoosing Your First Formicarium
When to move a colony out of the test tube, how to size a nest, and the main formicarium types compared — ytong, acrylic, 3D-printed, and more.
A formicarium is the artificial nest a colony graduates into once it outgrows the test tube. It’s tempting to buy a big beautiful nest on day one, but the single most important rule is size the nest to the colony you have, not the one you imagine — so this guide is as much about when and how big as it is about which.
When to upgrade
Keep colonies in a test tube longer than feels right. Move them into a nest when:
- The colony reaches roughly 20–50+ workers, or
- The tube fouls, moulds, or dries out and needs replacing anyway.
A small colony in a large nest struggles to maintain humidity and feels exposed — one of the common beginner mistakes is moving up too early.
Sizing it right
Choose a nest your current colony can fill within a few months. Many formicaria are modular, so you can add chambers or connect a second nest as the colony grows — a far better approach than buying oversized and hoping they spread out.
The main types compared
| Type | Humidity control | Visibility | Cost | Best for |
|---|---|---|---|---|
| Test tube | Excellent (built-in) | Low | Very low | Founding & small colonies |
| Ytong / aerated concrete | Good, passive | Medium | Low | Most beginners; DIY-friendly |
| Acrylic | Needs a hydration system | Excellent | Medium | Display & growing colonies |
| 3D-printed | Good, often built-in | Good | Medium | Growing colonies |
| Plaster / gypsum | Good | Medium | Low | Small–medium colonies |
Ytong (aerated concrete) is the classic beginner choice: cheap, easy to work, and naturally humidity-holding. Acrylic looks superb and shows the colony beautifully but is dry by nature, so it depends on you managing water. 3D-printed nests vary in quality but often include clever hydration. Plaster/gypsum holds moisture well but can grow mould if kept too wet.
Beyond the nest
Whatever you choose, you also need:
- An outworld (foraging area) connected by tube, with a solid escape barrier.
- Ventilation so the nest doesn’t become stagnant.
- A hydration method matched to the material — passive for ytong, active for acrylic.
Get the humidity and temperature right in the new nest with the heating and humidity guide, and see the starter kit checklist for the rest of the setup. When you’re ready to buy, our guide to choosing a UK seller covers what to look for.
Common questions
- When should I move ants out of the test tube?
- Usually when the colony reaches around 20–50+ workers, or when the tube fouls or dries out. Small founding colonies do better in a test tube far longer than most beginners expect — there's no rush.
- What is the best formicarium for beginners?
- For most beginners, ytong (aerated concrete) or a hydrated acrylic nest sized to the colony is the best first formicarium. Ytong holds humidity naturally and is cheap; acrylic offers a clear view but needs an active hydration system.
- What size formicarium should I get?
- Size the nest so your current colony can fill it within a few months. A colony rattling around an oversized nest struggles to hold humidity and feels exposed, which slows growth.
- Ytong vs acrylic — which is better?
- Ytong (aerated concrete) holds humidity passively and is forgiving and cheap, making it ideal for beginners. Acrylic gives the best visibility and a clean modern look but relies on you managing humidity with a hydration system.
Last updated 5 July 2026