152 ENTOMOLOGICAL NEWS. 



tition is completed its angles are filled up with sawdust, and 

 smoothed with a waxy secretion so as to make the bottom of the 

 next cell oval or rounded. These cells have a uniform depth of 

 five-eighths of an inch. Here I would like to ask if all the 

 Xylocopa make their tunnels wider in the centre of each cell than 

 elsewhere? I have been led to infer from the little literature I have 

 available, that in the construction of their cells they retained some 

 of the fragments wherewith to construct the partitions. This 

 seems to me rather too rational even for the carpenter bee, and I 

 thought I had solved the problem in supposing that' in digging 

 fragments for the formation of the partition the bee had uncon- 

 sciously widened the succeeding cell. This theory is untenable, 

 however, as I have found some apparently new tunnels with four 

 or five cells constructed exactly as when filled, and besides the 

 terminal cell is always so constructed. 



I have frequently seen it stated that the Xylocopa turns the 

 terminal cell towards the outer surface of the log so that the bee 

 resulting from the egg first deposited, and presumably the first 

 hatched, could eat its way out by a new channel. Whatever 

 may be the habit with other bees it is certainly not so with the 

 one in question, since all the bees here escape by the original 

 opening in the inverse order of their deposition. 



On opening many of the tunnels filled early in the season one 

 or two of the external cells may be found empty, the bees having 

 already made their escape. In the lower cells the bees though 

 perfect and active, remain until the following Spring, when they 

 break through the partitions and escape. In those built late in 

 the Summer all seemingly remain until the next Spring. 



How it happens that the bee resulting from the egg last de- 

 posited is the first to escape, when there must, of necessity, be 

 weeks of difference in their time of deposition, is something I 

 cannot satisfactorily account for. I am led to infer, by the fact 

 of the external cells always containing males, and the lower ones 

 only females, that the explanation in part lies therein. Probably 

 the males hatch out in less time than the females or take less 

 pollen to feed them, or it is very likely that both of these factors 

 enter into the equalization of the incubating periods. 



Fertile, though these insects are, yet on account of their many 

 enemies and parasites, comparatively few of them reach maturity. 



