520 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



As soon as tlie young caterpillars hatch they immediately go to 

 ■work to spina small silken web for themselves, which by their united 

 efforts 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 

 siiin unmolested. As they increase in size they enlarge their web by 

 connecting it with the adjoining leaves and twigs; thus as the}^ grad- 

 ually work downwards their web becomes quite bulky, and, 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 maturity, 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 treeihe f ood-supj^ily gives out, and they are forced by 

 hunger to leave their sheltering homes before the usual time. 



When the young caterpillars are forced to leave their web they do 

 not drop suddenly to the ground, but suspend themselves by a fine 

 silken thread, by means of which they easily recover the tree. Grown 

 caterpillars, which measure 1.11 inches in length, do not spin such a 

 thread. Both young and old ones drop themselves to the ground 

 without spinning when disturbed or sorely pressed by hunger. 



Pupa and Cocoon (Plate X, Figs. 2d and 2e). — 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 shelter 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 is of a very dark-brown color, smooth and polished, and 

 faintly punctuate. 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. 



The Moth (Plate X, Figs. 1 a-j, and 2/). — The moths vary greatly, 

 both in size and coloration. They have, in consequence of such vari- 

 ations, received many names, such as cwwea Drury, texto7^HajVV., punc- 

 tata Fitch, punctatissima Smith. But there is no doubt, as proven 

 from frequent breeding of specimens, that all these names apply to 

 the very same insect, or at most to slight varieties, and that Drury's' 

 name cunea, having priority, must be used for tlie species. 



The most frequent form observed in the vicinity of Washington is 

 white, with a very slight fulvous shade. It has immaculate wings, 

 tawny-yellow front thighs, and blackish feet. In some specimens the 

 tawny thighs have a large black spot, while the shanks on the upper 

 surface are rufous. In many all the thighs are tawny -yellow, while 

 in others they have scarcely any color. Some specimens (often reared 

 from the same lot of larvae) have two tolerably distinct spots on each 

 front wing, one at base of fork on the costal nerve and one just within 

 the second furcation of the median nerve. Other specimens, again, 

 have their wings spotted all over and approach the form pnnciatis- 

 sima, described as the Many-spotted Ermine-moth of the Southern 



* We have known the substantial cocoon of Cerura to be used for this purpose. 



