SUPERFAMILY TINEOIDEA 137 



causes the mines to become tentiform. During the fourth 

 and fifth instars the larvae pick out the parenchyma from 

 the fibrovascular network on the arched side of the mine. 



The typical Lithocolletiform mine, with the separated 

 lower epidermis drawn into folds and the parenchymous 

 tissue removed from the arched side, is not always adhered 

 to in this first group. Some species first separate the lower 

 epidermis of leaves, gather it into folds and feed on the 

 arched lower side, and some do not cause the surface of the 

 mine to be arched or tentiform. 



The mines of all species of the Cameraria group are on the 

 upper side of the leaves of their host plants. They usually 

 continue to be flat until just before pupation when one or 

 a few slight folds may be made in the upper cuticle. On 

 holding a completed mine to the fight its parts will be seen 

 to differ in transparency, the denser portion being that from 

 which the cuticle was removed in the early sap-feeding in- 

 stars, and the more transparent portion, that part of the 

 mine excavated by the larvae in their fourth and fifth in- 

 stars. 



Very many of the species are gregarious in larval habit, 

 the mines being occupied by several larvae extending the 

 mine at different points on its borders. 



The excrement of these larvae is not granular after the 

 third moult but seems usually to be somewhat viscous at 

 the time of deposition and is smeared upon the floor of the 

 mine. It is usually not very localized though in the com- 

 munity mines where the several larvae feed outwardly from 

 the centre, the borders are fairly clean. When solitary 

 larvae make elongate mines the excrement is usually scat- 

 tered along the middle of the mines. Probably the most 

 peculiar arrangement of excrement in this group is in the 

 mines of L„ tubiferella on oak. The mines are elongate, 

 and, gradually widening, continue to be about as wide as 

 the larvae are long. The larvae feed first on one side and 



