ORDER LEPIDOPTERA 45 



The tunnels do not go in straight lines but bend in very irregular 

 curves; as the caterpillar mines now on this side and now on that, 



it often crosses the tunnel already made Except for that 



one could easily tell the beginning of the tunnel or the place 



where larva began to mine At the beginning the place 



where the caterpillar commenced to mine, the tunnel is no bigger 

 than a hair but it goes on getting bigger all the way to the end, 

 where it is largest. 



These paths dug out in the leaf have a dull brown color from 

 their beginning for about half their length. This color is due to 

 the excrement which is enclosed there, taking up the whole mine. 

 But the other half, or rather more, is not entirely filled with 

 excrement; only all along the middle is seen a line or continuous 

 streak of brown excreta. The empty shells on either side appear 

 whitish because that is the color of the epidermis of the leaf. 

 I have noticed a rather curious thing about the excrement of these 

 little insects. In the first two quarters of the mine's length the 

 masses are perfectly continuous. Together they make up a single 

 body in the form of a thread which occupies the whole space of the 

 tunnel as we have just said. They have the appearance, then, of 

 having been liquid. The third quarter of the gallery is taken up 

 by excreta that hold together also, but which occupy only the 

 central part of the tunnel's width. A curious thing is that this 

 thread goes zigzaging in curves from one side to the other. In 

 the last quarter of the mine one may see that the excreta are no 

 longer zigzag, there they are in blackish grains placed in rows 

 along the passage-way. One may gather from these observations 

 that the excreta of our insects are not of the same consistency at 

 all ages, for when they were young they seem to have ejected 

 material in an almost liquid state and later this in the form of 

 grains which then must have had more solidity as they came 

 out. 



Our caterpillars do not enter the ground to transform, nor do 

 they remain in the leaves where they have hitherto lived. When 

 this critical time arrives (which is ordinarily in the middle of 

 October) they quit their tunnels; they pierce the upper membrane 

 and walk out on the leaf. They walk hither and thither, seeking 

 a suitable spot in which to undergo transformations. Those that 



