168 A NATURALIST IN HIMALAYA 



robber-fly lay astride the back of its prey, gripping 

 it tenaciously with all its limbs. So firm was its hold 

 that the victim could not possibly escape. The fore 

 tarsi of the fly were hooked round the anterior edge of 

 the front wings of the moth ; the median tarsi similarly 

 held the hind wings ; the hind tarsi closely grasped the 

 sides of the moth's abdomen, while the beak of the 

 Asilid was driven deep into the thorax a little to 

 the right of the median line. In such a grip a moth is 

 helpless ; its wings and abdomen are held as in a vice. 

 It resists, but its struggles are in vain. It rapidly dies 

 as its juices are sucked away. What strikes the mind 

 in a contest of this nature is the skill with which the 

 Asilid controls the wings of its prey and the strength 

 of its grasp from which there is no possible escape. 

 This insect needs no poison to stupefy its captures. 

 Its strength and skill suffice for all its needs. It can 

 overcome so powerful an insect as the cicada, and one 

 so well armed as the humble-bee. 



I paid more attention to those very common little 

 water-bugs, the Notonectidcz, known popularly as 

 water-boatmen. They were the most numerous 

 element in the society of the pool. I often wondered 

 why the frogs did not attack the boatmen, for it 

 was obvious that they never attempted to seize them, 

 though the boatmen often nibbled at the frog's hind 

 legs. I thought that most probably the boatmen were 

 possessed of an unpleasant taste ; yet this was not 

 so, for the frogs eagerly devoured dead boatmen when 

 thrown into the pool. The Notonectidce escape the 

 frogs by their great activity. The frogs recognize 

 their inferior skill and never attempt to attack the 

 boatmen. They have learnt that for these insects 



