246 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
coloration ; in fact nearly all the various color varieties may be found upon the same 
tree. The fall generation is, however, on the whole, darker, with browner hairs 
than the spring generation. 
As Boon as the young caterpillars hatch they immediately go to work to spin a 
small silken web for themselves, which by their united etforts soon grows large 
enough to be noticed upon the trees. Under this protecting shelter they feed in 
company, at first devouring only the green upper portions of the leaf and leaving 
the veins and lower skin unmolested. As they increase in size they enlarge their 
web by connecting it with the adjoining leaves and twigs; thus as they grad- 
ually work downwards their web becomes quite bulky, aud, as it is filled with brown 
and skeletonized leaves and other discolored matter, as well as with their old skins, 
it becomes quite an unpleasant feature in our public thoroughfares and parks. The 
caterpillars always feed underneath these webs; but as soon as they approach ma- 
turity, which requires about one month, they commence to scatter about, searching 
for suitable places in which to spin their cocoons. If very numerous upon the same 
tree the food supply gives out, and they are forced by hunger to leave their shelter- 
ing homes before the usual time. 
When the young caterpillars are forced to leave their webs they do not drop sud- 
denly to the ground, but suspend themselves by a fine silken thread, by means of 
which they easily recover the tree. Grown caterpillars, which measure l.»ll inches 
in length, do not spin such a thread. Both old and young ones drop themselves to 
the ground without spinning when disturbed or sorely pressed by hunger. 
Pupa and cocoon. — Favorite recesses selected for pupation are the crevices in bark 
and similar shelters above ground ; in some cases even the empty cocoons of other 
moths.* The angles of tree-boxes, the rubbish collected around the base of trees 
and other like shelters are employed for this purpose, while the second brood prefer 
to bury themselves just under the surface of the ground, provided that the earth be 
soft enough for that purpose. The cocoon itself is thin and almost transparent, and 
is composed of a slight web of silk intermixed with a few hairs, or mixed with sand 
if made in the soil. 
The pupa (Fig. 86, d and e) is of a very dark-brown color, smooth and polished, 
and faintly punctate ; it is characterized by a swelling or bulging about the middle. 
It is 0.60 inch long and 0^23 inch broad in the middle of its body, or where it bulges 
a little all round. 
The moth (Fig. S6 t f). — The moths vary greatly, both in size and coloration. They 
Fig. 87 .—Hyphantria cunea : a-j, wings of a series of moths, showing the variations from the pure 
white form to one profusely dotted with black and hrown. 
have, in consequence of such variation received many names, such as cunea Drury, 
textor Harr., punctata Fitch, punctatissima Smith (Fig. 87). But there is no doubt, as 
proven from frequent breeding of specimens, that all of these names apply to the 
* We have known the substantial cocoon of Centra tobe used for this purpose. 
