348 PHYSICAL GEOGRAPHY. 



the general surface, where the caterpillars had entered. They were not 

 attached to the rock or the moss, but lay in horizontal oval cells, evidently 

 formed by the movements of the caterpillar before pupation. The most 

 particular examination revealed no trace of any web or silken thread, 

 even as a lining of the cell. Mr. Sanborn's impressions, drawn mainly 

 from a comparison between the slender number of specimens he obtained 

 and the abundance of the butterfly, are, that the healthier caterpillars 

 penetrate even deeper into the ground ; but as I have also found them 

 under or beside surface stones, and Mr. Whitney has discovered larvae 

 ready for their change in similar localities, I am more disposed to believe 

 that the place to seek them is beneath and beside the uppermost stones, 

 and especially at the edges of the "rock rivulets," where the vegetation 

 is usually the freshest. To one familiar with the locality, a surface 

 almost completely strewn with angular rock fragments, Mr. Sanborn's 

 exploration will seem to have been a very successful one. Most of his 

 specimens were found at more than a mile from the summit ; doubtless 

 better success would attend efforts in localities not more than half or 

 three quarters of a mile from the top. 



One would suppose that insects, whose home is almost always swept by 

 the fiercest blasts, would be provided with powerful wings fitting them 

 for strong and sustained flight ; but the contrary is true. They can offer 

 no resistance to the winds, and whenever they ascend more than their 

 accustomed two or three feet above the surface of the ground, or pass 

 the shelter of some projecting ledge of rocks, they are whirled headlong 

 to immense distances, until they can again hug the earth. Their flight is 

 sluggish and heavy, and has less of the dancing movement than one is 

 accustomed to see in the Oreades.* They are easily captured. 



The European Aello appears, says Meyer-Dur, among the earliest but- 

 terflies of the Alps. It is seen soon after the snow melts, first, on the 

 lower grounds at the end of May ; last, on the higher levels (correspond- 

 ing more nearly to those to which our species is restricted) at about the 

 beginning of July ; it disappears in the same way from the end of June 

 to the end of the first week in August. 



2. Enodia Portlandia Scudd. Within the limits of New England this 

 is a very rare insect. It may be found occasionally upon the banks of 



* See p. 346. 



