120 HABITS. 



tion. They passed too high for recognition, al- 

 though, by his description of their size and their 

 mode of flight, it was probably the same butterfly 

 which we have just mentioned. 



The movements of butterflies on the wing are 

 as different as the flights of birds, and just as an 

 ornithologist may distinguish many birds by their 



FIG. 107. Cluster of Danais Plexippus, alighted on a bush ; reduced. 

 (After Thaxter.) 



mode of flight when their form and colors are 

 indistinguishable, so the observant entomologist 

 may often determine a butterfly from a consider- 

 able distance. In the case of the entomologist, 

 however, the decision is more difficult, since there 

 are such rapid replacements of one species by 

 another throughout the summer that direct com- 



