1900.] 33 



interesting point which this brief review of the larva) has brought out 

 is, that the eight British species seem to arrange themselves in pairs. 



THE MIISES AND COCOONS. 



In a state of nature the mines are invariably found on the under- 

 sides of the leaves ; but on one occasion having sleeved some mespilella 

 on a pear shoot, the moths became to some extent puzzle-headed 

 (owing perhaps to the novelty of the food-plant), and deposited a 

 portion of their ova on the upper-side of the leaves, in which position 

 the mines were subsequently found. For their shape and position 

 the mines probably depend much more on the size and character of 

 the leaf than on the particular species of larva. One general law 

 seems to guide the larva, which is, that directly it meets with one of 

 the principal ribs, it takes it for a base line and runs its mine alongside, 

 by this means ensuring that the long axis of the mine is in the direction 

 of the ribs, the importance of which for facilitating later on the con- 

 traction of the mine is obvious. Herein I believe lies the secret which 

 will explain most of the diversities of the mines. In large leaves with 

 prominent ribs the mines lie in the interspaces, and according as the 

 interspace is wide or narrow, do one or both ribs act as the guide or 

 boundary ; of the narrow interspace and its slender overlong mine the 

 leaf of the cherry {Prunus avium) is an example, whilst the wild service 

 {Pyrus torminalis) illustrates the wide interspace and shorter and 

 broader mine. On the other hand in a small leaf like the leaflet of the 

 mountain ash (Pi/rus aucujjaria) the midrib becomes the base line, and 

 the mine i^ confined to one or other lateral half. The ribs, however, 

 do not always determine the matter, for in all those instances in which 

 the mine is situated on the; edge of the leaf, the latter becomes the 

 base line. With most of the species this position is accidental, but 

 it is the rule with oxyac (uthce ; for this insect uses the lobes of the 

 . hawthorn leaf, usually only the tips, and follows their outline most 

 accurately. All the mines have the sides well drawn in, and are kept 

 scrupulously clean, the frass being collected into one large heap, placed 

 generally near the centre, but in those of oxijcicantlics and spinicolella 

 at one end. As regards size, the mine of oxyacanthod is distinctly small, 

 a single lobe of the hawthorn leaf or even one of its leafy stipules 

 sufficing, and so too for so large a species as that of pyrivorella, due 

 probably to the close texture of the pear leaf, the mine of spmicoJella 

 again is small ; in the others it is fairly large. But there is plenty of 

 variety, and a collection of hlancardella, say, might readily be made of 

 size as small as one of oxyacanthce selected on the opposite principle. 



