200 BUTTERFLIES 



ing leaves (in a continual fluttering in the case of the 

 trembling aspen, and to a less degree in the other food 

 plants), this of itself is a protection to it, as it would more 

 readily escape observation as an object distinct from the 

 leaves, all being in motion together; but on the more 

 stable leaves, like the willow, the motion in a feeble wind 

 would not be sufficient to be serviceable, and here, at 

 least, the packet comes into play. An object in motion 

 among others at rest is a noticeable thing; a fact well 

 recognized among animals, as a host of them show when 

 they fear being seen. This packet attached by loose 

 silken threads moves, as stated, with a breath of wind, and 

 so would distract attention from its architect near by, who 

 has taken pains to place it at the farthest remove from his 

 perch while still (to avoid undesirable steps) on his daily 

 track. If this be really its object, it is surely one of the 

 oddest devices in nature." 



The curious winter cases of the Viceroy were first 

 carefully described by the late Dr. C. V. Riley, in one of 

 his classic reports on the insects of Missouri. It is one of 

 the best accounts which has ever been written and is well 

 worth quoting at some length: 



" The larvae of the autumnal brood," wrote Doctor Riley, 

 "when about one fourth or one third grown, build for 

 themselves curious little houses in which they pass the 

 winter. First and foremost — with wise forethought and 

 being well aware through its natural instincts that the 

 leaf which it has collected for its house will fall to the 

 ground when the cold weather sets in unless it takes 

 measures to prevent this — the larva fastens the stem of 

 the leaf with silken cables securely to the twig from which 

 it grows. It then gnaws off the blade of the leaf at its tip 



