Ants in this laboratory nest are individually marked with dabs of paint to help researchers at the University of Arizona track their activities. Tucson, Arizona, USA
The prickly little beast on the right is a millipede in the genus Polyxenus. I found several of these living in the brood nest of a Temnothorax rugatulus ant, where they were probably scavenging on the ant's refuse. Huachuca Mountains, Arizona, USA
Temnothorax rugatulus, nest under a stone. Chiricahua Mountains, Arizona, USA