LLMENITIS I. 



stitute the base of the perch. This is bound and leno-thened with frass and 

 serves every purpose. 



Both these species of larva? have a habit of accumulating little scra})s of li-af 

 at the base and under side of the perch till quite a packet is formed, and this is 

 rolled back as the substance of the leaf is eaten so as to be close to the cut edtre 



o 



of the leaf This edge, in willow, is kept nearly square, a section being eaten 

 from one lobe rt'nd then a corresponding one from the other. In beginning on a 

 fresh section, the larva lies diagonally across one corner, the anal legs clasping 

 tht' l)ase of the perch, and its head will strike the side of the leaf about two 

 tenths inch above the corner. It eats a canal nearly perpendicular to the side 

 and towards the midrib ; not all at once, by any means, for this is the result of 

 several meals, in the intervals always I'eturning to the perch. When the rib is 

 reached, the larv;i then begins to feed on the lower side of the canal next the 

 rib, and to keep the slender and imsteady bit of leaf in position it spins guys 

 from the end and edge to the solid leaf opposite and to the rib. As the feeding 

 proceeds and a considerable triangle is held only by a narrow strip, which dimin- 

 ishes at each mouthful, more guA's are put out, and, at last, when the triangle 

 falls, it is held by the threads and swings to the base of the perch. If not, it is 

 soon brought there by fixing one thread after another from it to the rib and leaf 

 till it is pulled to its place. Here it is bound loosely. As other bits are added, 

 there comes to be an open packet, held together by simple threads, and of about 

 one tenth inch diameter. In the two vouuijer stao;es this is moved alono- as the 

 larva feeds, and is always kept close to the leaf, jiartly by pushing, what is gained 

 at each eflbrt being secured by threads, or it is rolled by attaching successive 

 threads from the farther side to the leaf and ri)> till the mass is turned over. 

 After the second stage the packet is left behind, and no additions are made to it. 

 (Fig. h). I was at first puzzled to account lor this construction ; but happening to 

 see one of the caterpillars back down the perch and drop its excrement directly 

 into the packet, it occurred to me that really this was the magazine whence the 

 larva drew its materials for lengthening the perch. On pulling some of the pack- 

 ets apart a few grains were always found in them. This I believe to be the use 

 of the packets, and without some contrivance to catch the frass, it is difficult to 

 see how the larva obtains the materials it uses. Apparently it drops just about 

 enough into the packet for the object in view, for it is certain that the grains aro 

 usually expelled wherever the larva happens to be, and fall to the ground. After 

 the end of the perch is sufficiently strengthened and there is no further need of 

 the grains, the packet is dropped behind and neglected. 



The larvaj oi Artltemls hatch in from seven to nine days, undergo two moults, 

 and construct, each for itself, cases or hybernacula of leaves in which to pass the 



