106 THE ENEMIES OF BUTTERFLIES [ch. 



exercised with a gentleness sufficient to ensure that the 

 butterfly reaps the reward of its disagreeable nature. 

 And unless, of course, the butterfly is allowed to do so 

 the enemy can play no part in the production or 

 maintenance of a mimetic resemblance. 



What is true for mantids is probably also true for 

 the other groups of predaceous insects. Dragon-flies 

 and wasps have been recorded as attacking the dis- 

 tasteful as well as butterflies of unprotected groups. 

 Among the most serious enemies of butterflies must I 

 probably be reckoned the blood-sucking Asilids. These 

 powerful and ferocious flies seize butterflies on the wing 

 with their strong claws and plunge their proboscis into 

 the thorax. Apparently they inject some swift poison, 

 for the butterfly is instantly paralysed, nor is there any 

 sign of struggle. The Asilid flies off with its victim, 

 sucking the juices as it goes. There can be no doubt 

 in the mind of any one who has watched these creatures 

 hawking butterflies that their natural gifts are such as 

 to enable them to exercise discrimination in their food. 

 Most insect life is at their mercy but they appear to 

 exercise no choice, seizing and devouring the first 

 flying thing that comes within easy reach. Certainly 

 as regards butterflies palatability or the reverse makes 

 no difference, and they are known to feed indiscrimin- 

 ately both upon the evil-flavoured and upon the good. 

 Taking it all together the evidence is such that we can- 

 not suppose predaceous insects to pay any attention to 

 warning colours, and, therefore, we cannot regard them as 

 playing any part in connection with mimetic resemblance. 



