262 THE BUTTERFLIES OF NEW ENGLAND. 



number on one plant. The spider that finds two eggs of a Basilarchia in 

 one day must be an excellent hunter. 



Escaped at last from these dangers, which only lasted at the most ten 

 days, the caterpillar crawls forth from its prison and begins its active life. 

 It is a scrawny juiceless looking thing, all covered with warts, and less 

 than any other newly born cater] )illar, would seem a tempting morsel even 

 to an ichneumon or a spider. Yet both make havoc with it at this time. 

 To a wandering ichneumon contact with an empty egg-shell would prob- 

 ably 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 devouring their egg-shells, and so 

 not leaving this " scent" behind them, would oftenest escape, and by de- 

 grees this habit would be perpetuated and fixed ; and so it is here ; almost 

 invariably 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 

 outmost leaACs 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 ? Ketreat down the leaf? That would be only to exchange one 

 danger for another, and on its way to a presumed place of safety it would 

 be more sure of detection, because a moving object in nature is always 

 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 nar- 

 row path and retiring always to the same spot. On this perch it cannot 

 be seen from beloAV, and from the sides and above seems almost or wholly 

 a part of the denuded midrib to which it clings ; more particularly when 

 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 (Notodonta) , feeding on 

 the very same })lant as species of butterflies with this hal)it (one in Europe 

 and one in America) ; while the caterpillars of Basilarchia employ a 

 further device, the actual im[)()rt of which has been a puzzle. Very soon 

 after birth, when it has eaten but a very few sw^aths 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, 



