LEPIDOP TER A. 
275 
the black border on the outer margin of the hind wings is 
narrower, and the subterminal light band on the fore wings 
is more distinctly marked. The early stages of this species 
are unknown; but the larvae of European species feed upon 
birch and poplar. With these the prolegs are all present; 
but the first three pairs are stunted. As this is probably the 
most primitive Geometer occurring in our fauna, we suggest 
the popular name Firstborn for it. In Germany an allied 
species is known as the Jungfernkind. 
Canker-worms .—In many parts of our country Canker- 
worms are extremely abundant. In such localities they are 
among the more important of insect pests, often completely 
stripping the foliage from fruit and shade trees. There are 
two distinct species of Canker-worms; but they resemble 
each other so closely that they were long confounded; and 
to this day they are distinguished only by entomologists. 
The two species agree in being loopers or measuring-worms 
in the larval state, in the possession of ample wings by the 
adult male, and in the adult female being wingless. They 
differ in structural characters, as indicated below, and also to 
a certain extent in habits. In one species the greater num¬ 
ber of moths mature in the autumn and emerge from the 
ground at this season; in the other species the insects re¬ 
main in the pupa state during the winter, emerging as moths 
in the spring. The two species are therefore appropriately 
designated as the Fall Canker-worm and the Spring Canker- 
worm respectively. 
The Spring Canker-worm, Paleacrita vernata (Pal-e-ac'ri-ta 
ver-na'ta).—The eggs are ovoid in shape, and are secreted in 
irregular masses, usually under loose scales of bark or be¬ 
tween the leaflets of the expanding buds. The larvae hatch 
about the time the leaves expand, and become full grown in 
from three to four weeks. They vary greatly in color, and 
are marked on the back with eight narrow, pale, longitudinal 
lines which are barely discernible; the two lateral lines of each 
side are much farther apart than the others; and there are 
