BUTTERFLIES OF THE DISTRICT OF COLUMBIA 119 



It shows a strong preference for flowers growing about 3 feet 

 above the ground, and 3 to 5 feet above the ground may be consid- 

 ered as the habitual feeding level of this butterfly. It will descend 

 to a foot to feed on clover or on the butterflyweed, or rise to 6 feet 

 to visit the topmost flowers on a thistle. Almost invariably it 

 chooses a flower more or less above, or at least not below, the general 

 level of the herbage. 



When feeding the females remain quiescent, but the males from 

 time to time suddenly open their wings to an angle of usually about 

 60° and immediately close them again. This action, which makes 

 them temporarily conspicuous from a long distance, may bear some 

 relation to the flocking habits. If another individual comes too 

 close to a feeding male the fore wings are suddenly drawn forward 

 and a few quick menacing flaps are given, causing the newcomer to 

 shy away. 



The milkweed butterfly is occasionally noticed circling about 

 muddy spots in roads or sitting on the mud and sucking up the 

 moisture. But it can not properly be regarded as a " puddle 

 butterfly." 



This is a very peaceful insect. The males display almost no 

 interest in one another. Occasionally two males are seen clumsily 

 flopping about each other, but they usually part in a second or two, 

 without having risen above the general level of their normal flight. 

 More rarely these half-hearted combats last for several seconds, and 

 the belligerent males will rise at a small angle to a height of 6 or 

 even 8 feet above the vegetation ; but the duelists seem never to suf- 

 fer any injury. The viciousness displayed by the males of most 

 butterflies toward one another is wholly foreign to the nature of 

 the milkweed. 



Persecution of other smaller butterflies is occasionally indulged in 

 by the males of the milkweed butterfly. I once saw a male flying 

 about 10 feet above the ground, turn from his course, and dive 

 through a group of three males and a female of the yellow clover 

 butterfly {C olios fhilodice)^ which were fluttering about together at 

 about the same height, scattering them in all directions, and I have 

 several times seen males dive like a hawk at yellow clover butterflies 

 flying beneath them. Once I observed (at Newton, Mass.) a male re- 

 peatedly pouncing upon a cabbage butterfly {Pieris rapue)^ which 

 dodged about near the ground trying to escape, and on another occa- 

 sion, at Cabin John, Md., I saw a male fluttering about a battered 

 female of the regal fritillary {Argynnis idalia)^ the two gradually 

 rising to a height of about 15 feet. 



But in spite of its essentially peaceful disposition the milkweed 

 butterfly is not wholly without courage, for it will attack most 

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