LLAIENITIS I. 



thick permanent covering to this gap ; which done, it worked back, drawing the 

 edges as before, and weaving, till at length the case was complete. (Fig. i.) 

 As it spun, the larva was in a constant state of anxiety about its work, as if it 

 foresaw the storms of rain and wind it must be subjected to for many long months, 

 sluit in this slender house. In closing, it lies along the midrib inside, its anterior 

 segments extending over the top, and it moves its head from side to side weaving 

 a concave edge. But it often reached far over and added a thread here and there 

 where the work seemed to be finished, and it would frequently leave the case to 

 inspect the fastenings about the branch, and to weave additional threads there 

 as needed. The silk is passed entirely around the branch, and binds both sides 

 of the leaf-stem. In weaving at tlie case the larva would soon lyecome ex- 

 hausted. I timed one activelj' at work for ten minutes, and there succeeded an 

 interval about as long of rest, the larva lying motionless along the midrib. 

 When at last the case is finished, the larva enters, and rests awhile, but presently 

 comes out, runs about examining the stem and the fastenings, then returns — 

 and this scrutiny will be repeated perhaps three or four times. Two larvag 

 were kept in the same glass, each of which had commenced a case and partly 

 inclosed it, when I removed one. The other soon began to amuse itself by 

 shifting about, trying each case and working at it, and finally completed and oc- 

 cupied that which it had not begun. Some days after all had apparently retired 

 for the season, one came out and wandered uneasily about, but a few hours later 

 was found to have returned to its case and was seen no more. 



There was some variation in the mode of cutting the pattern, as sometimes 

 work was begun on the side of the leaf instead of at the base. But it always 

 resulted in the same fiddle-shaped piece. The cutting was evidently fatiguing, 

 from the inconvenient position of body required, the head and anterior segments 

 having to ha bent sideways, even to a right angle much of the time, and the 

 larva frequently rested and shifted its place. It was never found on the wrong 

 side of the cut, however, or in danger of falling Avith the rejected portion of the 

 leaf Occasionally after having begun a case the larva would desert it and con- 

 struct another. The larvfe finally entered the cases head first, their bodies con- 

 tracting in length and proportionately thickening so as to completely fill the 

 vipper end of the tube, and allow nothing to be visible from the aperture, while 

 over this last the long flap of the leaf soon curved sufficiently to keej) out water. 



Prolmbly in natural state the case is constructed from the leaf on which the 

 caterpillar began its existence, whether willow or aspen. This is so with Disip- 

 inis. The ends of the leaves have been eaten away and only the sides need 

 shaping. But if the residue is insufficient, or for any reason does not answer 

 the purpose, the caterpillar moves to another leaf and begins cutting. 



