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XVIII. On the larva of the Tentliredinidi\3, loith special 

 reference to protective resemblance. By 

 P. Cameron. 



[Read June 5th, 1878.] 



The purpose of the following paper is to show that the 

 theory promulgated by Wallace,* in explanation of the 

 colours and markings of caterpillars, namely, that edible 

 larvffi are coloured so as to be invisible as much as possible, 

 and inedible ones so as to be easily seen, holds good Avith 

 the larvas of saw-flies. I purpose also showing that 

 caterpillars and saw-fly larvaj have the same style of 

 coloration and arrangement of the markings both in the 

 edible and inedible larvae, that is to say, that the former 

 are green, either entirely so, or if they bear any markings 

 these take the form of white or pink continuous lines 

 along the back or sides, while the latter have contrasting 

 colours; the markings are usually irregularly -arranged 

 dots, and they feed iu exposed positions where they are 

 readily noticed. 



I need scarcely point out how widely different the 

 Tenthredinid(B and the Lepidoptera are, how they belong 

 to two different orders, differing profoundly in almost 

 every detail of structure, and having no very close generic 

 affinity with each other. 



Let us first consider those saw-fly larvte, whose bodies 

 correspond in coloration with the substances upon which 

 they are usvially found. Many of these have flat bodies, 

 and rest when feeding upon the lower side of the leaf. In 

 every case they are uniformly green, with the head faintly 

 brownish, or it may be green, like the rest of the body. 

 A beautiful example of the flat green larvre we find in that 

 of Caviponiscus luridiventris, which seems indeed to have 

 been specially formed for this mode of life, being very 

 broad and flat. We have other instances in the luteus 

 group of the genus Nematus, which feed on the lower 

 surface of the alder leaves, and in Nematus pallescens^ 



* See Darwin's " Descent of Man," 2nd ed. p. 325. 

 TRANS. ENT. SOC. 1878. — PART III. (OCT.) 



