COLOURS AND FORMS OF INSECTS. 14I 



mons, the purpose of their superabundant production 

 would be frustrated. We have no doubt, indeed, that 

 insectivorous animals can instinctively detect their 

 prey, in all the usual modes of concealment, as 

 acutely as the practised eye of a naturalist, who can 

 with ease perceive what escapes the observation of the 

 inexperienced. When a woodpecker is taught by 

 Nature to detect a wood-boring caterpillar, by the 

 bark sounding hollow when tapped with his bill, and 

 wnen an ichneumon -fly can detect a chrysalis closely 

 rolled up in a leaf*, we should be strongly inclined 

 to doubt that colour or form could afford very effec- 

 tual concealment from enemies, though we readily 

 grant that many probable instances of this have been 

 adduced. Of these instances it may be well to give 

 a iew examples. 



The caterpillar of a nocturnal moth {Nuctua aliice, 

 Fabr.) is said to assume the colour of the lichens 

 upon which it feeds, being grey when it feeds on a 

 grey one {Parmdia sajcatUts, Ach.), and always 

 yellow when it feeds on a yellow one {Cetrariaju/ii- 

 perina^ Ach. t) ; the change of colour being (it is 

 alleged) intended by Providence to conceal it from 

 its enemies, as it becomes difficult to distinguish it 

 from the lichens. The caterpillar of the coronet-moth 

 {Acronycta Ligustri^ Ochseniieim.) which feeds 

 upon the privet, is so exactly of the colour of the un- 

 derside of the leaf, to which it usually clings during 

 the day, that a person may have the leaf in his hand 

 without discovering the caterpillar:); ; a circumstance 

 explained upon the same principle. This, indeed, is 

 no uncommon circumstance, as many caterpillars 

 very nearly resemble the colour of the leaves upon 

 which they feed ; and the wonder rather is, that so 



* See ' Insect Architecture,' p. 174-5. 



f FabrV orUsung. in Kiiby and Spence, ii. 220. 



X Brahm, Inseeten, in ibid. p. 221. 



