Annual Address of V. T. Chambers, Esq. 87 



the mine is enlarged no more, neither does the larva increase in length; 

 it is still of the length of the larva at the end of the fifth stage. The 

 ratio of growth has ceased. The body is less rigid and more conti-ac- 

 tile, and the head, hitherto in the axis of the bod}', is now somewhat 

 deflexed. This stage lasts only half as long as each of the previous 

 stages, about thirt3'-six hours, and at the sixth moult, as in the previous 

 moults, each organ can be seen to be retracted out of the corresponding 

 part of the larval skin. The larva, in its seventh stage, is at first 

 scarcely distinguishable from the sixth stage larva; it is onl}'' a little 

 less depressed, but it becomes gradually more cylindrical in the latter 

 part of this stage. It does not feed, and there is no increase in length, 

 nor is the size of the mine increased. This stage again lasts three 

 daj'^s, and near the end of it, owing to the changes going on within it, 

 by which it becomes a pupa, it becomes distinctly cylindrical, and is 

 no longer a " flat" larva. The spinneret and silk glands are more full^^ 

 developed, and capable of use, and they are brought into use. After 

 passing into this stage the larva remains quiet for some hours, then it 

 turns upon its back and spins a narrow web along the inner surface of 

 the loosened upper cuticle of the leaf, whereby a narrow fold is made in 

 the cuticle, so that a slight curve is given to that part of the leaf, and 

 thus the mine is made more roomy. Then the larva turns again on to 

 its ventral surface, and spins beneath it a circular floor of fine white 

 silk, the diameter of which is a little greater than the length of the 

 larva ; then turning again on to its back, it spins over it a circular 

 roof which is united to the floor of the mine all around its edges, and 

 its coccoonet is complete. It then turns again on to its ventral surface, 

 and rests quietl}' to undergo its seventh moult; that by which it passes 

 into the pupa state. It has now been in its seventh stage about two 

 days and a half, and in twelve hours more its change is complete. But 

 how is this change efl"ected? Just as were its previous changes, by the 

 absorption of some organs, or the arrest of their growth, and by the 

 rapid growth of others. If about six hours after the completion of the 

 cocoonet, the larva be removed from the mine, it is found to be 

 no longer a flat larva; it has become almost cylindrical, whilst the 

 thoracic feet are much enlarged, and appear as mamillary' projections? 

 and the arrangement of the oil globules is the same as we have seen it 

 to be just previous to each of the preceding moults. A little later we 

 shall see that great changes have taken place in the head, though up to 

 this time none of the organs of the forthcoming pupa can be perceived. 

 As in the preceding moults, the eye-spots, antennai and trophi arf gradu- 

 ally retracted from their corresponding parts of the old skir , and at 



