June, igoi.] Smith : On Some Digger Bees. *71 



same burrow : several bees then may be working in the same general 

 system, all more or less independent of each other. 



The conclusion was irresistible that there is no second brood : that 

 the bees dig to get out of the sun and keep on digging in a sort of 

 blind, instinctive way. They make all sorts of laterals and sometimes 

 make processes that resemble cell clusters, in isolated instances going 

 so far as to line individual cells with clay. But these clusters are 

 never complete ; there is never an enveloping or air space and the 

 drop cells or fingers are of all sorts of lengths. In short the struc- 

 tures are not breeding cells at all. All the bees found were females, 

 and the inference seems to be that after copulation they do more or 

 less work all summer in a hap hazard sort of fashion ; then late in the 

 season they deepen the main burrow to between four and five feet. 

 There from one to eight bees will pile on top of each other to go into 

 hibernation. Some of the bees that we dug out more than four feet 

 down, from burrows closed on top, were already almost dormant and 

 could be freely handled without their making effort to sting ; very 

 different from the bustling activity of the newly hatched individuals 

 or of those working on the brood cells. 



The really remarkable fact is that these bees that have been dig- 

 ging such long burrows during the summer, abandon them in the 

 spring and start all over again with new diggings for breeding pur- 

 poses. A single bee may, in the course of its life, dig two quarter- 

 inch tubes, which combined will equal between seven and eight feet 

 in depth ; and if the laterals and fingers can be added it would amount 

 to at least two feet more — one of the most remarkable instances of 

 apparently useless digging on record. Mr. Brakeley, as a matter of 

 curiosity, weighed two bees taken in one of the winter burrows, and 

 found them i J4 grains together ; the larger of the two weighed less 

 than one grain, and he put the problem thus : If a blue bee, weight 

 less than one grain, will dig a hole double its own diameter, 64 inches 

 deep, how deep ought a Princeton graduate, weight 185 pounds (or 

 thereabouts), diameter two feet (more or less), to burrow to equal blue 

 bee, weight for weight ? 



And he answers in this wise : One grain bee, 5 feet ; one pound, 

 bee, 7,000 grains — 35,000 feet or, roughly, 7 miles. This would 

 make for the Princeton graduate (or the Rutgers professor) 1,295 

 miles of tubing four feet in diameter ! But this does not tell the 

 whole story, for the calculation was made when we did not know that 

 each bee digs two burrows of approximately equal depth. 



