July— August iSSS.] 



PSYCHE. 



81 



which only lasted at the most ten days 

 the caterpillar crawls forth irom its 

 prison and begins its active life. It is a 

 scrawny juiceless looking thing, all cov- 

 ered with warts, and less than any other 

 newly born caterpillar, would seem a 

 tempting morsel even to an ichneumon 

 or a spider. Yet both make havoc 

 with it at this time. To a wandering 

 iclmeumon contact with an empty egg- 

 shell would probably mean, as a result 

 of its inherited wisdom, that some nice 

 young caterpillar was about, and the 

 neighborhood would be all the more 

 thoroughly ransacked. Caterpillars de- 

 vouring their egg-shells, and so not 

 leaving this '"scent" behind them, 

 would oftenest escape, and by degrees 

 this habit would be perpetuated and 

 fixed ; and so it is here ; almost invari- 

 ably the caterpillar hastens to destroy its 

 former prison walls, which it devours 

 to the very base, too closely glued to the 

 leaf to be eaten ; probably it breathes 

 more freely when that is done. 



But where does it now find itself? 

 Its food at its very feet, — yes ; but in the 

 most exposed position possible. Atop 

 the extreme tip of one of the out- 

 most leaves of a spray that projects 

 most freely into the sun and air, just 

 where it can most easily be seen by the 

 passer by ; this seems to be the case 

 nine times out of ten. It is, however, 

 probably the safest place from the 

 prowling spiders ; but surely not from 

 its flying enemies. What does it do.'* 

 retreat down the leaf .^ That would be 

 only to exchange one danger for an- 

 other, and on its way to a presumed 



place of safety it would be more sure of 

 detection, because a moving object in 

 nature is alway most easily noticed. No, 

 it eats the nearest bit of leaf down to 

 but not including the midrib, first on 

 one side and then on the other, and then 

 retires to near the tip of the midrib to 

 digest it ; subsequent meals it takes in 

 the same way, moving with excessive 

 deliberation along its narrow path and 

 retiring always to the same spot. On 

 this perch it cannot be seen from below, 

 and from the sides and above seems 

 almost or whoUv a part of the denuded 

 midrib to which it clings ; more partic- 

 ularly vv'hen the leaves are in motion by 

 the wind, as they usually are on the 

 trees on which it feeds, particularly in 

 the case of the aspen. 



That this mode of life is on the whole 

 an advantage to it is rendered probable 

 from the fact that there are two cases 

 known, in which it is followed very 

 closely by caterpillars of a moth {Noto- 

 donta)^ feeding on the very same plant 

 as species of butterflies with this habit 

 (one in Europe and one in America) ; 

 while the caterpillars of Basilarchia 

 employ a fnrther device, the actual im- 

 port of which has been a puzzle. Very 

 soon after birth, when it has eaten but 

 a very few swaths down the leaf, the 

 little fellow constructs a small and loose 

 packet from minute bits of leaf and other 

 rejectamenta, loosely fastened to one 

 another and to the midrib, close to but 

 scarcely touching the eaten edge of the 

 leaf, and as fast as the leaf is eaten, it 

 removes this packet (continually added 

 to until it becomes about as big as a 



