XVII HUNTING DIPTERA 241 



on the sandy tract. She will have dropped down 

 somewhere near her hole, whose entrance she will 

 now seek, marked since her last exit not only by 

 the natural falling in of materials, but by her scrupu- 

 lous sweeping. No ! she does not hesitate in the 

 least — does not feel about — does not seek. All have 

 agreed that the organs fitted to direct insects in their 

 researches reside in the antennae. At the moment 

 of returning to the nest I see nothing special in their 

 play. Without once losing hold of the prey the 

 Bembex scratches a little in front of her just where 

 she alighted, pushes with her head, and straightway 

 enters clasping the Dipteron to her body. The sand 

 falls in, the door closes, and the Hymenopteron is at 

 home. 



I have watched the Bembex return home a 

 hundred times, yet it is always with fresh astonish- 

 ment that I see the keen-sighted insect at once 

 detect an entrance which nothing indicates, and 

 which indeed is jealously hidden — not indeed when 

 she has entered (for the sand, more or less fallen in, 

 does not become level, and now leaves a slight de- 

 pression, now a porch incompletely obstructed), but 

 always after she comes out, for when going on an 

 expedition she never neglects to efface the traces of 

 the sliding sand. Let us await her departure, and 

 we shall see that she sweeps before her door and 

 levels everything scrupulously. When she is gone, 

 I defy the keenest eye to rediscover the entrance. 

 To find it when the sandy tract was of some extent 

 I was forced to have recourse to a kind of triangula- 

 tion, and how often did my triangle and efforts of 

 memory prove vain after a few hours' absence ! I 



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