THE WOOD-BORERS 



thousands of spiderlings. An acquaintance with Trypo- 

 xylon has shown us their fate, and has given us an illus- 

 tration of how closely the two groups are related. To 

 make a very modest estimate there must have been twenty 

 wasps at work in our straw-stack. During the six weeks 

 which make the busiest part of their working season 

 each of these must have stored, at the very least, thirty 

 cells, putting an average of ten spiders into a cell. It may 

 then be considered certain that the straw-stack, with its 

 working surface of twelve by twenty feet, was the mauso- 

 leum of six thousand spiders, and it is very probable that 

 twice as many were interred within its depths. It must 

 be remembered, too, that before the spiders have grown 

 large enough to be interesting to rubrocinctum, biden- 

 tatum has had her turn at them, and that those that are 

 allowed to grow too large for rubrocinctum are preyed 

 upon grade after grade, first by albopilosum and finally 

 by Pelopaeus, Pompilus, and other genera. 



The wasps of this genus lose their interest in family 

 affairs about the second week in August, though after 

 this time they may still be seen taking their well-earned 

 holiday on the blossoms of the aster and the golden-rod. 



