1900.] 31 



absent, not even an indication of the thoracic plate being discover- 

 able ; but the rule is not invariable, since there are a few species, 

 such as coryli, corylifoliella, and nicellii, in which the back is orna- 

 mented with a series of twelve large, black, square-shaped spots, a type 

 of marking common to many sorts of mining larvae, Coleopterous 

 as well as Lepidopterous. Eemoved from the mine, it is a most 

 helpless creature — it has no idea of crawling, all it can do is to shift 

 its ground slightly and in a spasmodic sort of way by an alternate 

 extension and contraction of the segments. Placed on its broad and 

 flat back, it is unable to right itself. 



This semi-footless condition is retained until the leaf has been 

 undermined to the full extent required, by which time the larva is 

 ready to lie up for its third moult, out of which it comes, to all ap- 

 pearance, a new creature. It is not only that fully formed legs make 

 their appearance, armed — the true legs with claws and the claspers 

 with booklets— but the whole aspect is altered. The flattened form 

 has been exchanged for a cylindrical one, the great predominance of 

 the thorax is gone, though the first segment still remains rather the 

 largest in the body, the hairs are long and conspicuous, and the head, 

 plump and of good fize, now assumes the ordinary position, with the 

 mouth directed downwards. The transformation is startling, and at 

 the same time ushers in a new set of activities. In place of the 

 arduous work of cutting and wedging a way beneath the skin of the 

 leaf, the larva now turns to and feeds at leisure upon its substance, 

 the mine having been converted into a roomy chamber by the con- 

 traction of the silk, which it was the first business of the larva under 

 the new conditions to throw across the separated cuticle or roof 

 from side to side. One more moult remains, the fourth and last. It 

 is with this moult that the various shades of colour and the blackening 

 of the plate and legs are acquired, which serve, so far as they go, to 

 differentiate the species. Thus, there are in all four moults, the 

 first two connected with the true mining life, the third or transforma- 

 tion moult, and the fourth or feeding-up moult. 



To come now to our own particular group : the mature larva? 

 are semi-transparent and yellow, with grey or blackish heads, chiefly 

 due to a broad dark stripe down each cheek, red mouth parts, a grey 

 or blackish tinge on the thoracic plate, and grey-spotted legs. The 

 intestine with its contents is plainly visible, but reduced in the full- 

 fed larva to so narrow a strip by the encroachment over it of the fat- 

 masses that it might reasonably be thought to be the dorsal vessel. 

 The changes rung upon these several characters lie within such narrow 



