March, igoi.] Smith: On Some Digger Bees. 33 



further investigations, and from a large number of casts and excava- 

 tions it was found, by April 30th, that the burrows made in March and 

 early April were gradually filling up, and that the heel of the cast be- 

 low a lateral, indicated the existence of a loaded cell or cells at lower 

 levels. A reexamination of the casts showed a heel present as early 

 as April 4th. As it happened, a cast had been made on that day which 

 for some reason was not at once taken up. Dug out on the 24th, a 

 heel was found and below it a loaded cell. 



April 23d, one cell was found in which the larva had apparently 

 just hatched, but no others of this character were discovered — all were 

 yet in the egg stage. This larva retained the position of the egg for 

 a long time, the mouth parts just touching the surface of the food 

 mass. Many of these cells taken up in the last days of April were 

 undoubtedly placed in the earliest burrows, hence the egg stage is an 

 unusually long one. 



By May ist Mr. Brakeley felt himself justified in writing as fol- 

 lows : " But several facts I have absolutely settled. She digs a very 

 crooked tube, depending on the soil status ; but generally starts in on 

 a crook. She first burrows to the full depth to which she is going, 

 begins to pouch at the bottom and the first egg is laid at the bottom. 

 Then she goes upward to start the second pouch. * * * Varies from 

 three to five pouches and then starts again in a new place." Except 

 that we never found more than four pouches connected with any one 

 burrow, all these conclusions were verified by later experience. Of 

 the cartridges secured at this time a number were placed in vials in 

 the hope of securing larvae and later stages ; but in no case did I suc- 

 ceed in getting any beyond the larval stage. 



May 1 3-1 6th I spent at Lahaway and, although I dug out quite a 

 number of cartridges, all loaded, I found none in which the larvae had 

 hatched. Nor did I find any new diggings at this time ; the Colletes 

 period was evidently over for that year, the females had done their 

 work and the brood for the next year was provided for. 



Mr. Brakeley's observations as to the rate of digging is that they go 

 down about 5 inches a day. This is easily ascertainable because of 

 the stratification of the sand and clay previously noted. The charac- 

 ter of the fresh soil at the surface from each burrow, tells almost 

 exactly how far down the specimen is, when once one is familiar with 

 the sequence of the layers. 



June 4th and 5th were again spent at Lahaway, and on this date no 



