112 THE BUTTERFLIES OF NEW ENGLAND. 



weakest flight known to butterflies. To this family alone, so far as human 

 oro-ans can perceive them, are confined the few sounds which are emitted 

 by butterflies, consisting mostly of rustling and crackling, and evidently 

 produced in some manner by the wings ; in other groups, to be sure, cer- 

 tain movements of the wings suggest sound, but none apparently is pro- 

 duced, none certainly that can be heard by us. There is also here a 

 greater variety of structure than is found in any of the other families of 

 butterflies. We need only point out the fact that a considerable number 

 of its subdivisions have been raised to primary rank by not a few natural- 

 ists. The coloring of the wings is also more varied than in other families, 

 and more than in any other will one discover a striking difference between 

 the coloring of the upper and under surface of the wings. As one departs 

 farther and farther from the lower Lepidoptera in ascending the families of 

 butterflies, one discovers a larger proportion of those which, when at rest, 

 raise the wings above the back and expose only the under surface, instead 

 of expanding the wings horizontally and so showing the upper surface, as 

 in moths. It is therefore ui)on the under surface of the wings of butterflies 

 that one should look for a greater variety of coloring than upon the upper 

 surface, at le.ast in the highest forms ; and this is exactly what we find. 



Here, too, occur the greatest number of cases of protective resemblance 

 and of mimicry. 



Nor is the interest especially attaching to this family confined to structure 

 and coloring alone. In habits and in life-histories the diversity of the type 

 is everywhere displayed. For there is scarcely any variation in the regu- 

 lar cycle of changes which every lepidopterous insect undergoes which is 

 not found within the limits of this family, and many are confined entirely 

 to it. They pass the winter in every possible stage excepting, so far as 

 known, in that of the egg, but including in one or other group every stage 

 of larval life. The caterpillars are more often social than in other groups. 

 There frequently enters also an element of lethargy even in mid-summer. 

 The behavior of caterpillars for their protection against their enemies is 

 exceedingly varied and interesting, and the forms of shelter constructed for 

 their concealment are equally varied. The mode of pupation is, as 

 already stated, different from that of any other group, in that they hang 

 by their tail alone, and in general quite freely, though there are a few in- 

 stances, as Cirrochroa and to a certain extent Chlorippe, in which the pad 

 of silk is 80 tightly woven to the surface upon which it is spun, and the 

 cremastral hooks of the chrysalis are spread over so long a surface that the 

 chrysalis, instead of hanging freely, lies with its ventral surface in close 

 proximity to the surface of rest. The method in which they accomplish 

 their transformations, from the caterpillar clasping the pad of silk with its 

 anal prolegs to the chrysalis whose hinder end, armed with little anchor- 

 like hooks, is withdrawn from the shrivelled skin of the caterpillar and 



