Coloration and Development of Insects. 75 



and, with scarcely an exception, to edible ones. Cladius 

 viminalis has these hairs, like the other species of this 

 genus, but they do not add in any way to its conspi- 

 cuousness, for they are pale and scarcely noticeable, and 

 therefore cannot be ranked with the hairs on the goose- 

 berry grub {Nematus ribesii), which undoubtedly tend to 

 render it more easily seen. 



From the pale woolly appearance of these hairs, and 

 from the fact that most of the larvse of Cladius are green 

 and inconspicuous, it is probable that C. viminalis and 

 C. aeneus, Zad., are the youngest species, and that the 

 hairs derived from the primitive pale-coloured ancestor 

 have been retained, although no longer aiding concealment. 



Now what is the use of these hairs ? I believe that 

 suggested by Meldola and Lubbock, * to prevent the ■body 

 throwing a sharp shadow on the leaf, which would certainly 

 happen if the bodies were perfectly bare. It is possible, 

 too, that the hairs in Cladius, and the spines in Blenno- 

 campa {e.g., B. genicu/ata), may in addition to this 

 purpose, serve as a protection against the attacks of ants 

 and other carnivorous insects. I believe the green, spiny 

 larvai are as a rule nocturnal feeders, resting motionless 

 during the day on the underside of the leaf. Such, at any 

 rate, is the habit of those oi Macrophya sturmi, \ Kl., which 

 feed in company, and they give out a bad smell. One 

 kind of larva of this class {Nematus compressicornis. Fab., 

 vallator, Voll.)^: has the curious habit of surrounding 

 itself with a wall of dried bubbles secreted by itself, appa- 

 rently as a protection against insects. 



In regard to this subject, I notice a very suggestive 

 remark by Fritz Milller, | which is very well illustrated by 

 certain Tenthredous larva;. He says (alluding to the 

 caterpillars of butterflies) that obscurely-coloured larvre 

 must either live solitary and hide themselves, or acquire a 

 bad odour and congregate together. These, by living in 

 companies, surround themselves with a fetid atmosphere, 

 and thus make their presence as efiectually known as if 

 they were gaudily coloured, or armed with hairs and 

 spines. This is precisely what we find with the larvas of 

 Eriocampa, and others, as mentioned in my last paper. 

 Eriocampa adumbraia appears to have reached the 



* Trans. Ent. Soc, 1878, 214. 



t Cf. Kaltenbach, Ffianzenfeinde, S3. 



X Cf. Vollenhoven, tijd. Ent., i., 191, pi. 12. 



^ Quoted Proc. Ent. Soc, 1878, vi. 



