122 



THE AMERICAN ENTOMOLOGIST. 



up after tlic fashion shown al. the left of Figure 



.SI, -with the huva iuside. This roll of the leaf 



in. 1 



opijc 



is genei ill\ quite nnifonii and is mule iii tht 

 following inannei . Lxtendiiig itsell on the inid- 

 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 

 l)oint. 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 tirmly join them nearly to (he 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 lo shield 

 itselt 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 papillie 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 

 fjreen, but the general hue is a dirty white, 

 owing to the entire surface being very closely 

 studded with white or whitish papilhu with 

 dark brown ones Interspersed. These promi- 

 nences are hemispherical, hard, opaijue, shill- 



ing, and the larva feels rough and harsh to the 

 touch. 



At each moult some of these papilla' dis- 

 ippeai, c-peLiallj all the brown ones, the body 

 iiici eases in si/c so that the head is smaller than 

 the thud scj-nicnt, the green color of the skin 

 bLconiLs nunc apparent, the body is softer to 

 till tou( li, iiid the whole larva assumes a neater 



ipptll IIKC 



[!•%'. S3.] 



(olor.^— Light ( 



Thus this larva has very much the sumo 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 raimickry 

 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 1^ 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 

 luid 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. 81, h) 



•l''i-ijm livf fiiU-ttrown speohiiens SLMit Iiy Mr. jrulilciuiin, 



sunkeu dots iU'M > i i 



liirgei-jjramiliithiii . i i ii 



l)lack aiul tin- V.-l lnK .m : .\ I in I 



Imig'l'hi'l'iM.'.li'v l.\ ;'i Mr'iislit' I'.hi.l. 

 liali;, thu lalii'V \:n-^v !iu.rc..)l-lii.-i 



narrow, cun>-triclt'(l, gn-eu, smni. 

 lirst segniuni . Segmi-uts 1 — ;! gradu 

 to last grailually siiialler.' Stigiua 

 tliickly gpamilatt'd than tergiim. 



xiiiail- 

 black 

 several 



