16 BUTTERFLIES 



Our knowledge of the scents given off by American 

 butterflies is very fragmentary, and it is highly desirable 

 that many more observations should be made upon the 

 subject. If collectors generally would make careful notes, 

 both in the field and upon the freshly killed butterflies at 

 home, we ought soon to be able greatly to extend our 

 knowledge. By holding the butterfly with a pair of for- 

 ceps, one can often determine whether the fragrance is 

 emitted. It is often helpful also to brush the hairs or 

 tufts where the androconia are attached, using a small, dry 

 camel's hair brush for the purpose. 



Butterfly Migrations 



Migration seems to be a general instinct in the animaj 

 world, developed when a species becomes enormously 

 abundant. At such times this instinct apparently over- 

 comes all others and the creatures move on regardless of 

 obstacles and conditions that may mean certain death to 

 the vast majority. Such migrations among mammals 

 have often been recorded, one of the most notable ex- 

 amples being that of the little lemmings which migrate at 

 periodical intervals in a way which has often been de- 

 scribed. Among the insects such migrations have been 

 frequently noticed, and the phenomenon has apparently 

 been observed oftener among the butterflies than in any 

 other group. Entomological literature during the last 

 hundred years contains a great many records of enormous 

 flights of butterflies over long distances, extending even 

 from Africa into Europe or from one part of America to 

 another far remote. As such migration is likely to happen 

 whenever a species becomes extremely abundant it prob- 



