270 MAPLE LEAF CUTTER THE CASES WHICH IT MAKES. 



as a grove of maples could be seen. And what appeared to be 

 most singular, whilst the maples growing in forests were every- 

 where affected in this manner, those standing alone as shade 

 trees in fields, and those planted around houses and along the 

 streets of villages remained green and wholly exempt from the 

 prevalent malady. 



The cause of this fading of the leaves was readily discovered 

 upon examination. They were found, when inspected, to present 

 the appearances which are very well illustrated, plate 4, figure 6. 

 The green parenchyma or pulpy substance of the leaf was de- 

 stroyed in spots and irregular patches, leaving only the fine net- 

 work of veins and the transparent cuticle. These spots were 

 commonly in rings or in segments of a circle, with the centres 

 green and unaffected. In addition to these, holes of a nearly 

 circular form appeared in the leaves, about a quarter of an inch 

 in diameter, with others of a smaller size. A dozen or more of 

 these holes were at that time found in almost every leaf. And 

 some of the pieces which had been cut out of the leaf, forming 

 these holes, might be observed, adhering like round scales to the 

 surface of the leaf, some on its upper others on its under side. 

 On elevating this scale from the surface of the leaf, another 

 smaller one was found beneath it, and between them was a small 

 white worm, which was evidently the artizan by whom all this 

 work had been done — cutting out these circular pieces from the 

 leaf to form a cloak for himself, and when hungry feeding upon 

 the pulpy substance of the leaf, thus forming the circular and 

 irregular spots seen upon it. Occasionally one of these scales 

 might be observed to move slightly along, the worm at such 

 times protruding its head from under the edge of the scale and 

 with its feet pulling its unwieldy domicil to another part of the 

 leaf. 



Generally the worm was found inclosed by three of these 

 round pieces which it had cut from the leaf probably at succes- 

 sive periods of its life. First was a small one upon its back, 

 about 0.18 long and two-thirds as broad, slightly concave on its 

 under, convex on its upper side. Next was a larger piece, of 

 similar form, placed on the under side of the worm, its edges 

 overlapping those of the first piece, its concavity facing the con- 



