118 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



out of sight. But sometimes it will fly diagonally upward until it 

 is lost to sight at a height of 200 feet or more and a distance of 

 several hundred feet. If there be trees or houses in its path it always 

 rises and flies over them, never passing around them. 



On emergence from the chrysalis milkweed butterflies immediately 

 begin feeding, and for three days spend nearly all the time on flowers. 

 On the fourth day they begin to lose their interest in flowers and 

 become restless. From noAv on their time is largely spent in wander- 

 ing about. 



It is an obvious fact that practically all examples taken on flowers 

 are fresh, and the fresher the individual the easier it is to catch. Old 

 and worn individuals are seen commonly enough, but are more fre- 

 quently observed in flight than on flowers. Early-spring examples 

 I have never seen feeding — only on the wing. 



Apparently the adult life of this butterfly is divided into two 

 phases, a period of intensive feeding during which no sex instinct is 

 manifested, and later a period of extensive wandering when feeding 

 is relatively infrequent, in the latter part of which reproduction takes 

 place. 



Though this butterfly feeds on the flowers of a considerable num- 

 ber of different plants, it is particularly fond of the blossoms of 

 the common {Asdepias syriaca) and the red {A. incwrnata) milk- 

 weeds, the butterfly weed {A. tuberosa)^ and the red clover {TrifoUmn 

 pratense). Late in summer it is especially to be seen on the floAvers 

 of the goldenrods {Solidago canadensis and other large species), the 

 joe-pye-weed {^Eupatorium purpmreum), and the thistles. In its 

 fondness for goldenrod it stands in sharp contrast to the swallow- 

 tails — and indeed to practically all the other late-summer butter- 

 flies — which are exceedingly partial to the thistles and pay little 

 attention to the goldenrod if thistles are available. 



When these butterflies are feeding, the wings are almost invariably 

 tightly closed over the back, and the fore Avings are drawn back 

 as far as possible between the hind wings; but sometimes, especially 

 in cloudy weather or after a rain, the males will feed with the wings 

 extended horizontally. The milkweed butterfly feeds in any position, 

 with the body from horizontal to vertical, or even extending at a 

 considerable angle to the vertical beneath the point of support; but 

 it prefers to feed with the body at a more or less considerable angle 

 with the horizontal and the abdomen pointing diagonally downward. 

 If there is any wind the insect always feeds on the lee side of the 

 flowers. If frightened while feeding it almost invariably jumps 

 directly upward in a line at right angles to the axis of the body 

 before it flies away. It never ducks downward or darts off to one 

 side after the fashion of the more active butterflies. 



