XVIII 



A PARASITE— THE COCOON 



I HAVE just described the Bembex hovering, loaded 

 with her prey, above the nest, and descending with 

 a vertical flight — very slow, and accompanied by a 

 plaintive hum. This cautious, hesitating mode of 

 arrival might suggest that the insect was examining 

 from above in order to find her door, and trying to 

 recall the locality before alighting. But I shall show 

 that there is another motive. In ordinary conditions, 

 when nothing alarms her, she comes suddenly, 

 without hovering or plaintive hum or hesitation, and 

 alights at her threshold, or close by. So faithful is 

 her memory that she has no need to search about. 

 Let us find out the cause of the hesitating arrival 

 just described. 



The insect hovers, descends slowly, mounts again, 

 flies off and returns, because serious danger threatens. 

 That plaintive hum is a sign of anxiety, and is never 

 produced unless there is peril. But who is the 

 enemy? Is it I, sitting by and watching? Not in 

 the least ; I am quite unimportant — a block unworthy 

 of notice. The dreaded enemy — the foe who must 

 be avoided at any price — is on the ground, perfectly 



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