140 NOTES ON ANTHOPHORA ABRUPTA 



species "builds mostly in steeply inclined or perpendicular clay 

 banks." Evidently, judging from my observations and those 

 of Walsh and Riley, Anthophora abrupta has a preference for a 

 perpendicular or steeply inchned surface. Under natural con- 

 ditions a compact clay bank is usually selected, for such a soil 

 type seems better adapted to the peculiar mining activities of 

 this bee and does not weather away so rapidly. A similar pref- 

 erence is exhibited by Anthophora stanfordiana Cockerell, a 

 western species. Kellogg (1905) found a colony of this latter 

 species near Stanford University, "in a roadside cutting exposing 

 a clayey bank." Nininger (1920) reports finding two colonies of 

 this same species occupying on one occasion, "the sunny slope 

 of a moist clay bank in the foot hills of the San Gabriel Moun- 

 tains of southern California", and another time, "a steep bank, 

 facing south at the shore of the bay", on Angel Island. 



Similar and different nest situations are chosen by allied bee 

 genera. Say writes that Entechnia taurea "digs a cylindrical 

 hole in a compact clay or adhesive earth on the side of a bank, 

 or in earth retained amongst the roots of an overturned tree." 

 Upon one ocdasion I found a colony of this same species located 

 in a perpendicular clay bank beneath a railroad ])ridge crossing 

 a stream at White Heath, Illinois. Clisodon terminalis Cresson, 

 according to the late F. W. L. Sladen (1919), nests in wood and 

 thereby differs biologically from the genera Anthophora, En- 

 technia and Emphor. Nichols (1913) has given us an account 

 of the situation selected by Emphor fuscojubatus Cockerell. This 

 species made numerous nest openings, "by the side of a road, 

 for a distance of about one-eighth of a mile, in soil consisting 

 of a mixture of clay, sand and pebbles." Grossbeck (1911) 

 says that Emphor bombiformis [ = fuscojubatus] "seems to prefer 

 hard, shaly soil in which to nest though small colonies occur in 

 sandier soil." 



B. Size of Colonies and Gregarious Habits 



A glance at figure 1 will show the portion of the l)ank occupied 

 by the bee burrows and figure 2 shows how close the Inirrows 

 are to one another. In order to get some idea as to how many 

 bees belonged to this colony and to examine the contents of 

 the cells, I dug from a fairly representative section of the 1)ank 



