84 Journal New York Entomological Society. [Voi. iv 



portion of a leaf, and gives it quite a different tone and appearance, as 

 seen from beneath. A larva of leporina seated beneath an unillumi- 

 nated leaf, precisely resembles one of these patches." It is the Ameri- 

 can representative of leporiua, my vnlpina, which Dyar fancies bear?, 

 in its position on the leaf, a resemblance to a spider's web. I have at 

 one time fancied that the larva of alni and finiaralis, had deterrent 

 colors, but conclude that it is a case of mimicry. The black body re- 

 sembles a wet twig, the creamy dorsal patches mould, while the spatu- 

 late hairs are like the filaments of club mosses. The somewhat slow 

 and stealthy movement which I have noticed in this to me repulsive 

 larva, adds to the deceptive likeness to these inanimate objects so com- 

 mon in the woods. The young larva of abii, resting in a curled posi- 

 tion on the leaf above, seems to imitate in its colors bird excrement. 

 With regard to the mimicry of caterpillars we must remember that 

 larvae are exposed to the attacks both of vertebrates and invertebrates. 

 Birds prey upon them, and they have every reason to fear the attacks of 

 insect parasites. The law of vision may thus be assumed to be the same 

 for the vertebrate as for the insect eye. Both the bird and the wasp 

 must be deceived by the appearance of ^//«' and oi funeralis, and pass 

 them over, if the mimicry is to be effective. It may be argued, from 

 the unity in the manifestation of mimicry, no general indications being 

 apparently offered, of mimicry working in two directions to meet different 

 visual conditions in its enemies, that it succeeds both with the bird and 

 the wasp in a percentage of instances. The original percentage, like the 

 original variation was small, but sufficient to establish the original di- 

 rection, and, once established, it is evidently worked out by heredity to 

 the condition in which we now find it. To be effective with the wasp, 

 as with the bird, the mimicry of alni must nroduce a similar effect upon 

 the retina of both ; in this case not only the form, but the color, must 

 be seen, both together suggesting to the brain of bird and insect not the 

 real, but a different, and, to them, indifferent object. The immunity is 

 probably only the result of cursory examination, but even this is suffi- 

 cient to justify the variation. So far as the larval groups in Apatela are 

 established, they partly show a special direction in the means to secure 

 immunity from their enemies. Thus the more typical forms of the sub- 

 genus Hyboma resemble foliage, while several species belonging to the 

 genus Pharetra seem deterrent. The general neutral gray tint of the 

 moths has been commented upon by authors as adapted to conceal them 

 from observation in their usual resting places, in the crevices of the bark 

 and against the trunks of trees. The moths which choose such resting 



