78 THE SOLITARY WASPS. 



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 ruhrocinctum. This species is very cosmopolitan 

 in its tastes, for we also found it utilizing the small holes in the 

 sticks of a wood-pile. 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 inhabi- 

 tants, and thus we often kept several sets under observation long 

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

 foimd Trypoxylon alhopilosuni nesting in holes made by beetles 

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

 tatwn, was very common, nesting in the stems of plants. Dur- 

 ing the month of August we saw many individuals of this spe- 

 cies hunting for spiders on the blackberry bushes, but at this 

 time we were so much absorbed in Crabro stirpicoJa that we 

 never followed them to their homes. 



Ruhrocinctum was more conveniently studied, and through 

 July and August we watched the comings and goings of these 

 little wasps. They were very good-tempered, never resenting 

 our close proximity nor our interference with their house-keep- 

 ing. By working hard they could prepare a nest, store it with 

 spiders and seal it up all in the same day. This we have seen 

 them do in several instances. In other cases the same operation 

 takes three or four days. In the second summer that we worked 

 with them we found one very energetic mother that stored four 

 nests in one day. It had rained hard on the twenty-sixth of 

 July and no wasp works in such weather. On the afternoon of 

 the twenty-seventh we took a straw just as the little mother was 

 bringing in a spider. We opened it and found that the inner- 

 most cell contained eight Epeirids, mth an egg on the abdomen 



