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 leporina , my vulpina , 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 funaralis , 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 alni , 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 
larvEe 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 alni and of 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 produce 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 
