June, 1901.] 



Smith : On Some Digger Bees. 



67 



In appearance the larvee were not in any way remarkable ; they 

 were fat, white grubs, the segments well marked, the head small, 

 horny and yellowish. Figure i gives a fair representation of it. The 

 pupa was, of course, the bundled-up adult with the sexual pieces much 

 more prominent. 



I was unable to find any reason for the presence of more than one 

 bee in a cast unless, in some instances, two or more work in common, 

 indicating the partial development of a social tendency. It seems 

 reasonable to believe that those burrows that contain only two clusters 

 with a few filled cells are made by one bee only ; but it is perhaps a 

 question whether a boring with three or more clusters is the product of 

 a single individual in any case. Cast number 

 7, was evidently compound and the clusters 

 are arranged in two series. The perpen- 

 dicular extended down simply from the sur- 

 face for 7 inches and was there divided into 

 two series, each of which had cell clusters. 

 Had there been two bees only it would have 

 been easier to refer the matter to a common 

 use of an entrance ; but four bees require an 

 agreement to use in common the entire per- 

 pendicular. 



There is a gap between July ist, and July 

 I2th-i3th, when I spent another two days 

 at Lahaway with Mr. Brakeley. On the 

 morning of the 12th I put down twelve and 

 Mr. Brakeley put down four casts in bee mine 

 No. 2. In working back to these casts we 



found, in uncast borings, a number of cell clusters with anywhere from 

 one to eight closed cells. All stages from the eggs to the fully col- 

 ored pupje were found, and 40 of the latter were put into closed vials 

 for complete development • both sexes being obviously represented. 

 A greater number of larvee and pupae were placed in alcohol. In 

 general the insects were in the pupa stage. The eggs were very few 

 and most of the larvre were full grown. 



It became increasingly evident that two or even three bees may 

 work from the same perpendicular. Three bees were found in one 

 cast in which there were five cell clusters. The relation of outer 

 empty to inner filled cells, was now conclusively established by care- 



FiG. 2. Pupa of Aiigoch- 

 lora htimeralis. 



