WASPS, SOCIAL AND SOLITARY 



her ordinary routine; and we noted with interest that the 

 change when it was made accomplished exactly what 

 was needed, the spider went in, but not too easily. 



In an experiment with a French Sphex which has 

 the habit of laying her cricket down at the threshold, 

 and going inside for an instant before dragging it in, 

 Fabre took advantage of the moment that the wasp 

 was out of sight below to move her prey to a little dis- 

 tance, with the result that when the wasp came up she 

 brought her cricket to the same spot and left it as be- 

 fore, while she visited the interior of the nest. Since he 

 repeated this experiment about forty times and always 

 with the same result, it seemed fair to draw the con- 

 clusion that nothing less than the performance of a 

 certain series of acts in a certain order would satisfy 

 her impulse. She must place her prey just so close to the 

 doorway; she must then descend to examine the nest; 

 and after that she must at once drag it down, any dis- 

 turbance of this routine causing her to refuse to proceed. 

 We once found a Sphex ichneumonea at work storing 

 her nest, and thought it would be interesting to pursue 

 Fabre's method and find out whether she were equally 

 persistent in following her regular routine. We allowed 

 her to carry in one grasshopper to establish her normal 

 method of procedure, and found that, bringing it on the 

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