Custom Canyon Foraging Area 7 (9x5x5) Fast formicaria 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

This adds $20 to the total price of the formicarium while adding on another 4x4" in nest space the colony can use as an expansion

This product is available for immediate shipping and ships within 2-3 business days after ordered

A Phalanx owner's video of their small Dorymyrmex insanus colony:

Custom Canyon Foraging Area 7 (9x5x5) Fast formicaria I would recommend a mediumThis is a medium foraging area style with raised platforms and other decor fitting of a higher elevation area in the same space. This provides additional surface area for ants to foraging on, and a second level of areas for feeding dishes.