148 NOTES ON ANTHOPHORA ABRUPTA 



attached to the entrance of the burrow. When a bee reaches 

 the end of the burrow or tube and has in its custody a wet pellet 

 of clay it presses the pellet against the outer edge of the tube 

 with the ventral surface of the abdomen and the posterior legs. 

 The head and mandibles also take part in the final shaping of 

 the pellet on the end of the tube. As this operation is performed 

 in summer, the clay quickly dries and becomes an integral part 

 of the tube. The exterior surface of the tube is never polished 

 and hence remains rough. The interior surface, however, is 

 smooth as a result of the polishing given it by the abdomen as 

 the pellets are fastened on at the end. A similar instance of the 

 abdomen "being used as a trowel" is recorded by Nichols for 

 Etnphor fuscojubatus. Grossbeck also has observed similar 

 actions on the part of the same species. The fissure on the top 

 of the tube appears to be due to the fact that Anthophora ahrupta 

 has an aversion to standing upside down while joining the 

 pellets onto the tube. Not one of the bees I observed at this 

 work ever assumed an absolutely upside down position, though 

 all would work around on the edge nearly to the top. The 

 definite course of each burrow was very difficult to trace. It 

 seems that each female makes her own burrow and then digs 

 lateral branches from the main stem which form the cells. I 

 never managed to decide how many brood cells each female 

 made and provisioned, but judge they are not numerous. 



H. Anthophilous Habits 



On July 3, 1919, some of the bees returning to the nest were 

 loaded with pollen. Bees so engaged in pollen storing seemed 

 to have less difficulty in finding their burrows than those still 

 in the midst of their mining operations. This is probably to 

 be explained on the basis of a longer acquaintance with, and 

 occupation of, their burrows, coupled with associative memory. 

 On July 11, 1919, all the bees flying to and from the bank ap- 

 peared to be females and were busily engaged in storing their 

 cells with pollen and nectar. Robertson (1891, 1894, and 1896), 

 in Illinois, records males and females as visitors to Asdepias 

 piirpurescens, Hydrophyllum virginicum, Mertensia virginica, 

 Convolvulus sepium, Pentstemon pubescens, Pentstemon laevigatus, 

 Rosa humilis, Rosa setigera and Gillenia stipulacea. Banks 



