Michener and Kerfoot (1967) describe the nesting and social biology of Caenaugochlora costaricensis (called Pseudaugochloropsis costaricensis in their paper) based on the excavation of 21nests near San Jose, Costa Rica, in July and August (tropical wet season). This bee has a bladk head and thorax with purple highlights, and a brassy abdomen. About two thirds of the nests are small (pre-worker brood emergence) and inhabited by lone females (the nest foundresses). These foundresses initiate the nests alone, and provision between one and six offspring cells, which will emerge to become the brood of female workers in the nest. After provisioning these cells, the foundress females cease foraging, and remain in the nest until the brood finishes developing. The mothers probably die at this time. No individuals with dramatically worn mandibles or wings, suggestive of older age, were found in larger colonies, suggesting that the foundress female did not survive to be the queen of a social nest. Multi-female nests, then, are semi-social aggregations of females of the same generation. Females apparently cooperate in provisioning brood cells, as only one cell is open at any one time. These bees constructed nests by burrowing tunnels into vertical banks. The nest consisted of a tunnel burrowing into the soil, then opening onto a larger gallery which contained an earthen cluster of cells supported by earthen pillars and/or rootlets of plants in the soil. After the emergence of the worker brood, colonies expand the cell cluster. Nests can contain up to 40 occupied cells. The authors provide illustrations of nest architecture, and photos of the clusters and brood cells. Seven females was largest adult population recorded. Among social colonies, there was no size difference between reproductive (with developed ovaries) queens and non-reproductive (without developed ovaries) workers.
