194 iNIr. P. Cameron 07i the 



wliose body corrosponds in coloration witli the leaf of 

 Salix- cinerea, its food plant. These larvas are very 

 sluggish. 



Another gronp of harmless larvas feed along the margin 

 of the leaf. They have cylindrical bodies, the colom- 

 green, or if they bear any markings, these take the form 

 of Avhitish or pinkish dorsal or lateral stripes. We have 

 said that they feed along the outer edge of the leaf. 

 Necessarily, in feeding, they cause indentations in the leaf. 

 The indentations are very regular, are cut clean as if by a 

 pair of scissors, in shape they are oval or semi-circular. 

 When feeding, the larvte keep their bodies closely pressed 

 to the leaf, and if there be a curve, either a natural one or 

 made by th^ :nselves, they follow its shape. We may 

 point out as examples of this habit, Nematus miliaris, 

 N.fagi, N.fallax, and others. 



It is a matter of familiar observation to collectors of 

 Lepidopte?'a, that most caterpillars, which feed on grass or 

 narrow-leaved plants, are green, either entirely so, or with 

 white or reddish continuous stripes, and so it is with the 

 saw-fly larvfe. In Nematus it is the case Avith N. cnprece, 

 N. conductu vhich feed on carices and grasses respec- 

 tively, with ±\. fallax, which is attached to the little trail-, 

 ing willow kSalix fusca, with N. rumicis on Rumex, N. 

 mysoitidis on clover, Taxonus glabratus on Polygonum, 

 and many others. In the Ent. M. Mag. XI. p. 66, the 

 Ilev. John Hellins relates how similar in coloration the 

 larva of the moth Erastria fuscula and that of a saw-flv, 

 which feeds on the same grass, are to each other, and he 

 proceeds to say that " he will leave it to some one else to 

 guess which of the two is the first wearer, and Avhich the 

 mimic of the colours of their common dress." But it is clear 

 that here Ave .,re no case of mimicry, but rather that both 

 acquired the same garb through its being that AAdiich 

 aftbrded them the greatest protection, similar habits and 

 similar surroundings having led to identity in coloration. 



It is equally Avell knoAA'n to Lepidopterists that pine-feed- 

 ing caterpillars assimilate very closely in coloration Avith 

 the pine leaves. This is so Avell known that I need 

 scarcely quote instances ; it occurs with Avidely different 

 families of moths. The same thing occurs Avitli the saAv-fly 

 larA^te. I may mention as examples Nematus Erichsoni, 

 Lophyrus virens, and many others.* One of the finest cases 



* They feed resting perpendiciilarlj, which is seldom the case with 

 lirvffi attached to broad-leaved plants. " 



