122 



THE AMEEIOAN ENTOMOLOGIST. 



lip after the fashion shown at the left of Figure 

 81, with the larva inside. . This roll of the leaf 



[Fig. 82.] 



Culoi'.s— Coppery-red and h 



is generally quite uniform, and is made in the 

 following manner: Extending itself on the mid- 

 vein, with its head towards the base of the leaf, 

 the larva attaches a thread to the edge, at about 

 one-fourth the distance from the base to the 

 point. By a tension on this thread, it draws this 

 edge partly toward the opposite one, and fastens 

 it there, being assisted in the operation by the 

 natural tendency of the leaf to curl its edges 

 inwards. Fastening a thread here, it repeats 

 the operation until the edges meet, and then it 

 proceeds to firmly join them nearly to the apex, 

 leaving a small aperture through which to pass 

 the excrement. During hot days the larva 

 remains concealed in the leaf, and towards 

 evening comes out to feed, though sometimes 

 it feeds upon its house, eating the leaf down half 

 way from base to point. It then abandons it 

 and rolls up a new one. In the breeding cage, 

 when placed in a cool shady room, the larva 

 seldom rolls up the leaves, but feeds at random 

 over the plant, and when at rest simply remains 

 extended on a leaf. From this we may infer 

 that its object in rolling the leaves is to shield 

 itself from the rays of the hot August and Sep- 

 tember sun ; for the plant invariably grows on 

 high naked prairies. 



The young larva has a large head, larger than 

 the third segment, which is the largest in the 

 body. The head preserves its general form 

 through the successive moults : it is light bluish- 

 green, thickly covered with papilla; of a dirty 

 white color, and there are also a number of 

 light orange papillae of a larger size scattered 

 among them. The skin of the caterpillar is 

 green, but the gene>-al hue is a dirty white, 

 .owing to the entire surface being very closely 

 studded with white or whitish papillas with 

 dark brown ones interspersed. These promi- 

 nences are hemispherical, hard, opaque, shin- 



ing, and the larva feels rough and harsh to the 

 touch. 



At each moult some of these papilhv dis- 

 appear, especially all the Brown ones, the body 

 increases in size so that the head is smaller than 

 the third segment, the green color of the skin 

 becomes more apparent, the body is softer to 

 the touch, and the whole larva assumes a neater 

 appearance. 



[b'iS. «.] 



Colors— Ijiglit orawge-ljrown aurt darkbrowu. 



Thus this larva has very much the same pe- 

 culiar whitish glaucous-green color as the plant 

 on which it feeds; and any one who has seen 

 it upon the plant, cannot help concluding that 

 it furnishes another instance of that mimickry 

 in nature, where an insect, by wearing the exact 

 colors of the plant upon which it feeds, is en- 

 abled the better to escape the sharp eyes of its 

 natural enemies. When full-grown, which is 

 in about three weeks after hatching, this worm* 

 (Fig. 81, a) measures IJ inches, and although, 

 as above described, the little elevations fre- 

 quently disappear so that it looks quite smooth, 

 yet sometimes they remain until the transform- 

 ation to chrysalis takes place, as was the case 

 with two which we bred. 



Preparatory to transforming, it suspends itself 

 by the hind-legs to a little tuft of silk which it 

 had previously spun, and after resting for about 

 twenty-four hours with its head curled up -to 

 near the tail, it works off the larval skin and 

 becomes a chrysalis. This chrysalis (Fig. 8r,,6) i 



* From five fuU-grown speciiiieus seut by Mr. Muhlemftn, 

 we draw up the following description. JjenetU 1 51) inches. 

 Cylindrical. (.Jeneral appearance shagreeneu pale glaucoits- 

 greeu, lighter above .stigmata than elsewhere. Ground-color 

 of body clear green Thickly covered with white papllhe 

 or gradulations, which are olten interspersed with minute 

 black or dark brown sunken dots. Heatl quite large (rather 

 more than -2- as large as the 8rd segment), nutant, subquad-- 

 rate, bilobed, graiuilated like the body, but with the black 

 sunken dots more numerous, and having besides, sevei-al 

 larger granulations above, some four ol which are generally 

 black and the rest fulvous; a row ot three very distinct eye- 

 spots at the b.ise of palpi; the triangular V"Shaped piece 

 e.ongated and well defined by a fine black line, and divided 

 longitudinally by a straight' black line; palpi and labrum 

 pale, the latter large and conspicuous; jaws black. Neck 

 narrow, constricted, green, smooth and retractile within 

 flrst segment. Segments 1 — S gradually larger and larger; 3 

 to last gradually smaller. Stigmata lUlvous. Venter less 

 thickly granulated than tergum. 



