IN THE GENUS BASILARCHIA 27 



ransacked. Caterpillars devouring 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 

 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 posi- 

 tion possible. Atop the extreme tip of one of the 

 outmost 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 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 



