Labyrinth (1026 Black) Fortress I would recommend a medium

I would recommend a medium sized nest for them because the chambers and tunnels for the Pioneer are larger on average than some of our other nests

All Mini Hearths with this feature can be used In this way

This smaller version of the Labyrinth formicarium

Tunnels and chambers carved to your size specifications (see drop-down menu)

Labyrinth (1026 Black) Fortress I would recommend a medium***This product is ready to ship. Ordering this product you will receive the exact formicarium in the photo.*** See the Labyrinth formicarium original product page here. Features: Dimensions 5x7" Nest (125mm x 175mm) and 8x4x4" Foraging Area (200mm x 100mm x 100mm) Decor Per Photos Medium Large Species size tunnels and chambers Water Towers 2 XL Water Towers Removable Vent (Optional) Museum Glass (Optional)