100 THE COMMONER BUTTERFLIES. 



distract from itself the attention of an enemy; for, by con- 

 stant removals, it is always kept close to the eaten edge of 

 tlie leaf, while its own perch is as far out on the stripped 

 midrib as it can find a good footing. After the second 

 moult it pays no further attention to this packet, and 

 retires for its siesta to the leaf-stalk or neighboring twig, 

 but it does not quit its feeding spot until the leaf, always 

 excepting the midrib, is almost or quite devoured, when it 

 passes to a neighboring leaf. The chrysalis state lasts from 

 nine to fourteen, usually ten to twelve, days. The butter- 

 fly, one of our most striking species, is a northern form, 

 hardly occurring, except in elevated regions, south of New 

 Hampshire, and frequents shaded roads, particularly in the 

 forest. It is perhaps as a rule single-brooded, though a 

 second brood, feeble in numbers, is known to occur; the 

 first brood appears in the latter half of June and remains 

 upon the wing until early in August; the second brood, 

 when it appears, comes very late in August and early in 

 September. The insect hibernates as a half-grown cater- 

 pillar, and to do this constructs, like all the si^ecies of the 

 genus, a singular hibernaculum : selecting a growing leaf 

 of its food-plant, it eats away the apical third or fourth, 

 excepting the midrib and a narrow flange on each side of it; 

 or it uses the leaf it has been eating, already trimmed in 

 this fashion; it then draws together, above, the outer edges 

 of the uneaten portion to construct a tube, which it lines 

 very heavily with brown silk, within and without; further 

 than this, it binds the leaf-stalk to the stem with repeated 

 windings of silk to prevent its falling to the ground in the 

 winter; by means of the ledge formed by the projecting 

 midrib, it then enters its tube head foremost and com- 

 pletely fills it, so that the 02:)ening is just closed by the 

 roughened end of the body. In the spring it quits its 

 winter home as soon as the first tender leaves have appeared. 

 A form called proserpina, a hybrid between this species 



