124 THIRD ANNUAL REPORT OP 



for this purpose, though it frequently spins up under fence boards and 

 in other sheltered situations. The cocoon is very much like that of the 

 common Tent-caterpillar, being formed of a loose exterior covering of 

 white silk with the hairs of the larva interwoven, and by a more com- 

 pact oval inner pod that is made stiff by the meshes being rilled with 

 a thin yellowish paste from the mouth of the larva, which paste, 

 when dried, gives the cocoon the appearance of being dusted with 

 powdered sulphur exactly as in that of the other species. Three days 

 after the cocoon is completed the caterpillar casts its skin for the last 

 time and becomes a chrysalis of a reddish brown color, slightly dusted 

 with a pale powder, and densely clothed with short pale yellow hairs, 

 which at the blunt and rounded extremity are somewhat larger and 

 darker. In a couple of weeks more, or during the forepart of June, 

 the moths commence to issue, and fly about at night. This moth (Fig. 

 52, J? ) bears a considerable resemblance to that of the Common Tent- 

 caterpillar (Fig. 51), being of a brownish-yellow or rusty-brown, and 

 having two oblique transverse lines across the front wings. It 

 differs, however, in the color being paler or more yellowish, especi- 

 ally on the thorax; in the space between the oblique line being, even 

 in the males, usually darker instead of lighter than that on either 

 side; but principally in the oblique lines themselves being always 

 dark instead of light, and in a transverse shade, often quite distinct, 

 across the hind wings. As in Americana, the male is smaller than 

 the female, with the wings shorter and cut off more squarely. Con^ 

 siderable variation may be found in a given number of moths, but 

 principally in the space between the oblique lines on the front wings 

 being either of the same shade as the rest of the wing, or in its being 

 much darker; but as I have found these variations in different indi- 

 viduals of the same brood, bred either from Oak, Hickory, Apple and 

 Rose, they evidently have nothing to do with the food-plant. The 

 scales on the wings are very loosely attached, and rub off so readily 

 that good specimens of the moth are seldom captured at large. So 

 much for the natural history of our Forest Tent-caterpillar. 



THE LARVA SPINS A WEB. 



From the very moment it is born till after the fourth or last moult, 

 this caterpillar spins a web and lives more or less in company; but 

 from the fact that this web is always attached close to the branches 

 and trunks of the trees infested, it is often overlooked, and several 

 writers have falsely declared that it does not spin. At each succes- 

 sive moult all the individuals of a batch collect and huddle together 

 upon a common web for two or three days, and during these periods 

 — though more active than most other caterpillars in this so-called 

 sickness — they are quite sluggish. During the last or fourth moult 

 they very frequently come low down on the trunk of the tree, and, as 

 in the case of the gregarious larvae of the Hand-maid Moth (Datana 



