in the actual position of the counter-shaded creature, rather than to its back- 

 ground. With this explanation we can proceed to a more particular de- 

 scription of these wonderful larvae. They feed, and, unlike most caterpillars, 

 rest, on the edges of leaves, and as their weight always draws downward the 

 edge to which they are clinging, they are to some degree caterpillars of the up- 

 side-down habit, and accordingly must have, in order that their appearance of 

 solidity shall be effaced, an inverted obliterative gradation of light-and-shade. 

 Unlike the larger counter-shaded caterpillars, such as the Luna, which cling to 

 stems far in among the foliage, they are usually fully exposed to view, on the 

 edges of outside leaves, and hence it is imperative that their surface, perfectly 

 flattened in appearance, should imitate as closely as possible the leaf-texture. 

 The degree to which this is achieved is one of the most exquisite and wonder- 

 ful things in the whole field of protective coloration. No caterpillar is harder 

 to detect, at the closest range, than is one of these beautiful leaf-edge larvae in 

 its natural position. The minute reticulate markings of the healthy leaf- 

 surface are closely copied on the larva's counter-shaded body by small dark 

 flecks, and, in addition, he often wears facsimile pictures (rendered perfect 

 by the same process of counter shading) of leaf-disease-spots. These spots, 

 and even the general coloring, vary somewhat in size and shape, but always 

 within limits beyond which the disguise would begin to be impaired. We 

 have seen many such caterpillars, representing several species and probably 

 several mere varieties. As a rule, it seems to be true that one kind of tree 

 harbors only one kind of 'leaf-edge' larva, which is almost or quite peculiar to 

 it, and rarely to be found on any otherplant. In the case of the beech, however, 

 which feeds a greater variety of particularly interesting ' disguised ' larvae than 

 any other tree we know, we have found three quite distinct species of the leaf-edge 

 class infesting it, and one of them, whose coloration is less distinctive than that 

 of most, is pretty often found on other trees. Again, the form inhabiting 

 certain kinds of maple, and wearing the deep-red spots of diseased maple trees, 

 occurs also on witch-hazel, and its spots are then usually browner and smaller.* 



* Possibly we are here speaking of two species. 

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