126 ON THE CATERPILLARS 



colour, with longitudinal rows of blackish spots, and with 

 numerous smaller dots of the same colour, each of which 

 emits a small black hair [in short, it is then by no means 

 unlike the larvae of the Shark-moths, Cucullia Scrophularice 

 and Verbasci, which both feed on the same plant], but 

 after its last moult, whilst still in the larva state, it assumes 

 a uniform greenish colour, with a slight fleshy tinge. This 

 larva also, like many others, after its last moult has the 

 skin very much wrinkled transversely, and, as it were, 

 composed of a very great number of short rings. So also 

 the larva of Nematus Grossularice, previous to its final 

 moult, is of a green colour, tinged with yellowish, especially 

 towards the head and tail, with numerous small black tuber- 

 cles. After its last moult it looses all these tubercles, be- 

 comes smooth and of a yellowish white colour, with the two 

 fore and two hind segments citron-coloured. 



The majority of these larvae feed, externally, on the leaves 

 of plants and trees ; occasionally, as in the case of the turnip 

 and gooseberry saw-flies, occurring to so great an extent as 

 to become the cause of real injury to the farmer and horti- 

 culturist. In general the entire substance of the leaf is 

 consumed ; the mid-rib and a few of the stronger ribs being 

 only left to show the extent of the devastation ; but other 

 species content themselves with eating only one of the sur- 

 faces of the leaf, leaving the other entire ; some, again, live 

 in galls resulting from the wounds made by the parent fly in 

 depositing her eggs ; one, at least, lives in the larva state 

 within the leaf in the manner of the mining larvae of some 

 of the genera of Micro-Lepidoptera, and another species, 

 like the larvae of some Tortricidce, lives in the interior of 

 fruits. Most of the species live singly (as the Cimbices, 

 Cladii and TentUredinidcB) y but others are social ; some of 

 the latter (as various species of Lyda) residing in a large 



