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Eickwort and Eickwort (1973) describe the social and nesting biology of Augochlorella comis (then called Augochlorella edentata) from a population studied near Turrialba, Costa Rica. This is a small (6-7 mm long) bright metallic green bee that occurs from Mexico to Panama. The authors excavated 21 nests.
Augochlorella edentata excavated tunnel nests into vertical earthen banks. The nests consisted of a turret of soil at the entrance, surrounding a tunnel leading to a gallery, in which a cluster of one to eight earthen cells (avg. 2.6) was supported by thin soil pillars (the authors provide illustrations). These nests were isolated (rather than aggregated).
Nests could be solitary or social. 43% of nests contained a worker in addition to the queen (up to four workers, but typically one or two). Ovarian dissections revealed that only one queen was present in each nest. The queens and workers were of the same generation (not mother-daughter associations), which would make the multi-female nests semi-social. There were no body size differences between queens and workers. The nests were apparently initiated by the workers and queens together, as co-foundresses. The authors found no evidence of re-use of nests or of cells within nests, although they allow that the bees may have cleaned out old cells so well as to not leave any evidence of re-use. The authors note that their study only examined the nests in July and August, so it is unknown if workers later found their own nest, or if daughters from the queen remain in the nest as workers, meaning the semi-social colonies would be eusocial.
Males were not present in the nests, but patrolled the nesting area attempting to copulate with the females. The males slept in an aggregation on a fern frond near the nesting area.