122 LEAF-MIXING INSECTS 



wider than their own small bodies. This part of the mine is 

 notable for its erratic angling and bending. Moreover, 

 here and there are a few narrow branches from this linear 

 tract which end blindly and so narrowly that it seems that 

 no larva could have turned around in their narrow confines, 

 but rather that, arriving at the place where these end so 

 abruptly they had capriciously changed their minds about 

 the way they wished to go and had slipped backward, to 

 start at another point in another direction. This linear 

 portion of the mine is a few centimeters in length. The 

 character of the mine then changes to a blotch but the 

 larvae still feed on sap and shear through only one layer of 

 cells. The blotch is irregular in shape being somewhat in- 

 fluenced by the position of the veins. In area it is somewhat 

 less than half a square centimeter. The frass of all this 

 sap-feeding period of mining is finely divided and adheres 

 in rather smeared particles to the upper cuticle of the mine — 

 for the larva does this part of the mining while lying on its 

 back. 



After a second moult the larval form changes to one very 

 much more like that of a normal free-living caterpillar, the 

 head capsule becoming oblique to the plane of the body. 

 The larvae are still very small, being less than 2 mm. in 

 length. They loiter for a while in the confines of the blotch, 

 move around, now with the venter down, and pick out 

 parenchymous tissue from between the tiny veins in the 

 floor of the mine. The excrement of this period is in more 

 definitely rounded and larger particles which seem to be 

 dryer at the time of deposition for they no longer adhere 

 to the wall of the mine. They are more or less collected 

 into one of the places cleared of parenchyma and they are 

 slightly webbed together with silk. 



When only a little more than half of the parenchyma has 

 been removed — picked in little patches here and there 

 from the floor of the mine — the larvae moult again. After 



