82 EEPORT UPON COTTON INSECTS. 



induce them to feed upon other plants, all resulting negatively. Even 

 when the larvae were placed upon plants closely allied to cotton they 

 starved. Still there is reason to believe, as will be shown later, that 

 another food-plant exists in Wisconsin at least. 



When full grown, the larva folds one edge of a leaf over its body and 

 fastens it down with yellowish silk. It then spins a delicate cocoon about 

 itself. At times, when the cotton- worms are very numerous, it frequently 

 occurs that the foliage is so badly eaten that is with difficulty that the 

 worms find a leaf in which to web up. Their endeavors to conceal their 

 bodies before pupating are at such times very amusing. The merest 

 fragment of a leaf is called into service ; and frequently very vigorous 

 struggles ensue between rivals endeavoring to secure the same place. 

 Often, too, the trouble of the successful competitor does not end with his 

 webbing up. Other larvae not yet fully grown, finding this remnant of a 

 a leaf, devour it, exposing the pupa, which either falls to the ground or 

 hangs suspended by some of the silken fiber which happens to be attached 

 te the uneaten frame work of the leaf. A detailed description of the larva 

 is appended. This will serve to distinguish the cotton- worm from other 

 larvae which are sometimes mistaken for it. 



ALETIA ARGILLACEA, Hiibner. 



Full-grown larva. 



Length, If inches (41 mm ). Color, light-green, striped with white and black, and 

 spotted with black and yellow ; in many individuals, especially those of the earlier 

 broods, the black stripes are wanting. Head, ochre-yellow, with thirty black spots, 

 from each of which arises a short, stiff, black hair (13 a). Body, light-green, with dorsal 

 line, two subdorsal lines, and lateral line white, and with numerous intensely black 

 piliferons spots. The more conspicuous of these spots are arranged as follows: Eight 

 forming two transverse rows of four each on the dorsal part of the first body seg- 

 ment (prothorax) ; a simple transverse row of four on each of the two following seg- 

 ments (in these two rows the inner spots are much smaller than the outer ones) j 

 on each of the eight following segments (first to eighth abdominal), four spots, form- 

 ing the angles of a square ; a row of spots on the lower subdorsal line, one spot on 

 each segment; below these, three spots, forming a triangle. In the green varieties 

 the piliferous spots are surrounded with white, and are thus rendered more conspicu- 

 ous ; spiracles black. Usually a row of indistinct yellow spots upon and above the 

 upper subdorsal line. All legs pale-green ; claws of thoracic legs black ; first pair of 

 abdominal legs rudimentary ; second pair half as large as third pair. The distribution 

 of black varies greatly in different specimens. In some there are no black stripes, this 

 color being almost entirely absent, except in the piliferous spots described above ; in 

 other specimens all that part of the body above the lateral line, excepting the dorsal 

 and subdorsal lines, is black. The following grades between these two extremes may 

 be fotind : 



a. Dorsal line bordered on each sid<- with black ; varies in width in different speci- 

 mens from those in which it is a mere line to those in which the entire space between 

 the dorsal line and the upper subdorsal line is black. 



6. Similar to variety a, except that the space between the subdorsal lines is also 

 black. 



c. Similar to variety b, except that the space between the lateral line and the lower 

 subdorsal line is more or less black. Aiitenn;e three jointed, basal joint large, fleshy ; 

 second joint about one-third the length of first joint, and often not visible, being with- 



