THE GENUS ACRONYCTA AND ITS ALLIES. 199 



In a very pale larva, the black dorsal area is only pronounced 

 between the anterior trapezoidals, and is then brown rather 

 than black, the subdorsal yellow is not defined from the 

 marblings of the area, below which, the colour is rather of a 

 pale greenish yellow with black spots than dark, as in other 

 specimens. The white spiracles, so conspicuous in a black 

 larva, are here hardly seen. 



When ready to spin up, this larva voids some damp frass, 

 very unlike the dry material of a feeding larva, and shrinks 

 very much in bulk, diminishing in length from 45 to 33 mm., 

 whilst the colours lose all definition and brightness. Rtiviicis 

 loses little or nothing in bulk before spinning up. It suggests 

 itself to me, that the food of venosa, being bulky in proportion 

 to its nutritiousness, the larva is, for its accommodation, more 

 expanded than in the other Viminia, though aiiriconia has a 

 good deal of the same habit of shrinking and voiding moist 

 frass before opening. This is, indeed, I believe, really a very 

 universal habit, though varying much in degree, the large ^A\i- 

 worxns, yama-mai, cecropia, etc., voiding some actual fluid when 

 preparing to spin. 



In its habits, the larva is not unlike the other Viminia. 

 The young larvae take each a line of cells in the leaf of the 

 grass or reed, and eat the surface between the septa on either 

 side, and, as they are at first somewhat gregarious, they have 

 a processionary aspect, attacking adjacent series of cells, and 

 this habit lasts into the 3rd skin, when they are more indepen- 

 dent and devastate the leaf more thoroughly. Some gregarious 

 larvae pine and refuse to eat when solitary ; of all the larvae I 

 have experimented with, this is most marked in Endromis ver- 

 sicolor when young. But I think there is a decided amount of 

 the same habit in Viminia, at least in venosa, auricoma, and 

 menyantJiidis, when small, and would be in rumicis, were he 

 not so hardy as to stand much ill-usage with impunity. 

 Isolated rumicis in their ist skin seem disconsolate, and they 

 all wander about till they find their brethren. They coil up 

 when disturbed, and when larger, have a curious way of 

 apparently desiring to drop when coiled up, but really 

 retaining a hold by the anal prolcgs. Venosa does not coil 

 up so readily and completely as the others. 



The cocoon is of whitish silk, and made amongst dead grass, 

 leaves, bits of reed, or any other available debris. It has a 

 rather weaker place at the top for emergence ; the colour of 

 the silk is very like that of auricoma. The cocoon is perhaps 



