THE WOOD-BORERS 



across the opening about an inch from the outside of the 

 wall. Later we found nests of the same species in the 

 posts which support an upper balcony of the cottage; 

 and here, too, the wasps made use of holes which were 

 already excavated. 



In the following summer we found large numbers of 

 these wasps at work in a straw-stack. The stack had 

 been cut off perfectly smooth on one side, so that many 

 thousands of the cut ends of the straws were exposed 

 to view, and these proved very attractive to rubrocinc- 

 tum. This species is very cosmopolitan in its tastes, for 

 we found it utilizing the small holes in the sticks of 

 a woodpile. The straws made the daintiest nesting- 

 places, however, and were well adapted to our purposes, 

 since they could be drawn out of the stack and split 

 lengthwise so that the contents could be easily studied. 

 The two halves could then be brought together again 

 without injuring the inhabitants, and thus we often 

 kept several sets under observation long enough to 

 watch the changes from the egg to the pupa. We found 

 Trypoxylon albopilosum nesting in holes made by beetles 

 in posts and trees, but never in straws. A third species, 

 bidentatum, was very common, nesting in the stems 

 of plants. During the month of August we saw many 

 individuals of this species hunting for spiders on the 

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