NEST ARCHITECTURE AND ASSOCIATED BEHAVIOR OF THE NOCTURNAL BEE, SPHECODOGASTRA TEXANA ( Hymenoptera : Halictidae )*

Sphecodogastra texana is a bee active at dusk and continuing through the night when the moon is up. The only flower observed to serve as a pollen source is Oenothera rhombipetala. Nests are made in stabilized sand. Each consists of a deep, straight, vertical burrow with a smaller lateral extending to each cell. An unusual feature is the lack of closure at the anterior end of each completed cell, the distal part of the lateral or rarely the whole lateral being open. The proximal part of the lateral, next to the main burrow, is ordinarily filled with sand. Another unusual feature is that the secreted lining of the cells covers only the lower surfaces of the cells, the other parts being unlined. Most nests contain only a single female and there is no evidence of a worker caste.