The Hunting Wasps 



precision that keeps them in the rear on the 

 same straight Hne; if she advances, they ad- 

 vance; if she retreats, they retreat, letting 

 the Wasp set their pace all the time, now 

 flying slowly, now coming to a stand-still, 

 according to the behaviour of their leader, 

 the Bembex. They make no attempt to 

 fling themselves on the object of their cupid- 

 ity; their tactics are confined to keeping 

 ready, in this rearguard position, which will 

 save them any hesitation at the critical mo- 

 ment. 



Sometimes, wearying of this obstinate pur- 

 suit, the Bembex alights; the others instantly 

 settle on the sand, still in the rear, and do 

 not budge. The Wasp darts off again, 

 with a shriller whimpering, a sign no doubt 

 of increasing indignation; the Midges dart 

 after her. One last method remains of 

 throwing off the persistent Flies: dashing off 

 at full speed, the Bembex flies far away, ho- 

 ping perhaps to mislead the parasites by rapid 

 evolutions across country. But the wary 

 Gnats are not caught in the trap: they let her 

 go and once more take up their positions on 

 the sand around the burrow. When the 

 Bembex returns, the same pursuit will begin 

 all over again, until at last the parasites' ob- 

 320 



