156 



THIRD ANNUAL REPORT OF 



These curious little cases may be commonly found upon our wil- 

 lows or poplars in the winter time. I have examined hundreds of 

 them, and although they are invariably built upon the same plan, 

 they vary greatly in the degree of perfection which the architect at- 

 tained ; and this is especially the case when they have been built in 

 confinement. The blade on the tip piece is sometimes gnawed off 

 right down to the rib ; at others it is left almost as broad as the tube. 

 Sometimes it is bent over the orifice ; at others not. They are also 

 much more irregular and ungainly when made from 

 broad leaves such as those of the Silver poplar, 

 than when made from the more narrow leaves of 

 the Willow. These autumnal larvas have also an- 

 other peculiar habit not heretofore recorded, and 

 which was first pointed out to me by Mr. J. A. Lint- 

 ner, of Albany, N. Y. They exhibit a tendency to 

 build from the time they are born, and will always 

 "a. eat the leaves from the side, gnawing large holes 

 and cutting along the sides of the mid-rib, as at 

 Fgure 71, a. They commence at the tip and as they 

 work downwards towards the base, they collect the 

 debris into a little bunch, which they fasten with 

 silk to the mid-rib. When the hibernaculum is fin- 

 ished the seam is perfectly smooth and the whole 

 inside is lined with silk. The larva, after completing its work, com- 

 poses itself for the winter, with the tail towards the orifice. Here it 

 remains till the catkins are in bloom the next spring, when it retreats 

 from its house and commences feeding. Not the least wonderful part 

 of the phenomenon is, that it is only the autumnal brood of larvae 

 that form pitcher-like houses to live in during the inclement season 

 of the year, the summer brood having no occasion to shelter them- 

 selves from the cold. We thus have an instance of a curious archi- 

 tectural instinct being only developed in alternate generations ; 

 which is much the same thing as if, with a certain race of men, the 

 great-grandfathers, the fathers and the grandchildren ran wild in the 

 woods, and the grandfathers, the sons and the great-grandchildren 

 lived in houses and led the life of civilized human beings. 



When we duly consider this peculiarity in our Disippus larva, we 

 may well pause and ask — 



What wondrous power enables it so well, 

 The coining cold of winter to foretell, 

 And to provide for its long torpid rest, 

 A house, from means at hand, the very best i 



We can but admire the beautiful adaptation of means to an end 

 — no matter how we choose to explain it! There can be little doubt 

 but that many of the phenomena in animal life which we so summa- 

 rily dispose of by the ready use of that rather blind term "instinct," 



