The Origin of the Markings of Caterpillars. 341 



Unfortunately I have not hitherto been able to 

 make any experiments with birds. It would be 

 rash to conclude from the experience with lizards 

 that ring-spots were of no biological value. There 

 is scarcely any one means of protection which 

 can render its possessor secure against #// its foes. 

 The venom of the most poisonous snakes does 

 not protect them from the attack of the secretary 

 bird (Serpentarius Secretariats) and serpent eagle 

 (Spilornis Cheeld) ; and the adder, as is well known, 

 is devoured by hedgehogs without hesitation. It 

 must therefore be admitted that many species 

 which are protected by distastefulness, may possess 

 certain foes against which this quality is of no 

 avail. Thus, it cannot be said that brightly 

 coloured caterpillars, which are not eaten by birds 

 and lizards, are also spared by ichneumons. It is 

 readily conceivable therefore, that the larva of 

 D. Euphorbia may not be unpalatable to lizards, 

 because they swallow it whole ; whilst it is perhaps 

 distasteful to birds, because they must hack and 

 tear in order to swallow it. 



From these considerations it still appears most 

 probable to me that D. Euphorbia, and the nearly 

 allied D. Dakliiasid Mauritania, bear conspicuous 

 ring-spots as signs of their being unpalatable to 

 the majority of their foes. The fact that these 

 species feed on poisonous Euphorbiace<%> combined 

 with their habit of exposing themselves openly by 

 day, so as to be easily seen at a distance, may 



