Please refer also to the following link for details on this group:
Hylaeidae = Link 1
Clausen (1940) considered this family under the Apoidea, noting that they were a small family of primitive bees that make their nests in stems of plants, in burrows in the soil, or in various holes and crevices. Several members of the principal genus Hylaeus (Prosopis) have been observed in Hawaii by Perkins and are stated to live at the expense of other bees of the family, although the exact relationships were not known.
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Cockerrel, T. D. A. 1939. Bees from the Caroline and Palau Islands and Yap (Hymenoptera, Apoidea). Occasional Papers of the B. P. Bishop Museum, Honolulu, Hawaii 15(5): 61-66.
Cockerell, T. D. A. 1942. Bees of the family Hylaeidae from the Ethiopian region Smithsonian Inst., Washington, D.C.