THK MIGRATIONS 0¥ BUTTERFLIES. 1083 



regaling themselves, soon start olV to rcsnnie tlieir jonrncy with their fellow travellers, 

 moving again amongst tliem as before and l)ound for the same destination. It is 

 curious to observe that butterflies of a totally difl'erent kind, wlien they liappen to 

 come within the range of one of these moving columns, are, for a period, carried 

 away apparently by the same impulse and fly in company with it. but are soon seen to 

 be moving ort' indopeudently as at tlrst. 



Another instance in tlie same family is our Anosia plcxippus, for an 

 account of whose movements, \vhich I believe I have shown good reason 

 to consider periodic, the reader is referred to that species and especially to 

 pp. 727-737, 741-74.3. To tiie accounts there given of its swarming upon 

 trees may be added that of Mrs. Bush of San Jose, Cal., wlio writes to 

 the American naturalist : — 



I have been to Monterey, and was fortunate enough to see the "butterfly tree," or 

 trees, as there are three of tliem. These trees are the Monterey pine (Pinus insignis 

 Dougl.). and are probably over one and a half feet in diameter, and completely cov- 

 ered with live butterflies. To say that there were as many butterflies as leaves upon 

 ttie trees would not be a very great exaggeration. I saw them in the morning when 

 it was cool and they could not fly very well, and piclied up a dozen from the grass in 

 a few seconds. A lady resident informed me that for the twelve years she had lived 

 there the appearance had been the same, (xv : 572.) 



Since tiie printing of those pages, the following account of the migratory 

 movement lias been given by Dr. Ellzey, as observed at West River, Md., 

 Sept. 23, 1886 :— 



About 7 o'clock in the morning my son, G. Murray Ellzey, called the attention 

 of myself and several other gentlemen to the fact that "the whole heavens were 

 swarming with butterflies." There were an innumerable multitude of them at all 

 heights from, say, 100 feet to a height beyond the range of vision, except by the aid 

 of a glass. They were flying due southwest in the face of a stifl'breeze. Observations 

 upon the flight of individuals between points of known distances apart showed that 

 the rate of movement was not far from 20 miles per hour. Where they originally 

 came from or whither they went we could not tell. They undoubtedly came from be- 

 yond the bay, which, in that place, is 14 miles across, and they must have been early 

 on the wing. By 11.30 o'clock the numbers had declined, audit was evident the bulk 

 of the flight was over, but for several days a gi-eat many individuals, evidently fol- 

 lowing the migratory movement, were observed. My brother-in-law, Mr. Daniel Mur- 

 ray, who had Ijeen three days previously, viz., on the 20th of September, at Long 

 Green, in Baltimore County, Md., saw a vast multitude of the same butterflies in mi- 

 gratory movement ; they were seemingly exhausted in flight and settled on the trees 

 in such multitudes as to give them the appearance of an autumnal forest. (Insect 

 life, i:221.) 



I had also overlooked the statement by Werneburg that the Deutsche 

 Ronianzeitung (1872, 319) mentions a passage of this butterfly in Con- 

 necticut in 1871 towards the southwest, which passed at a height of from 

 100 to 160 metres overhead in endlosen massen. 



The most common examples, however, of migrating butterflies are to be 

 found in the subfamily remaining to be considered, the Pierinae, where 

 more than elsewhere thei'e is a remarkable general propensity for congre- 

 gating, these being among our .most social butterflies. Instances of this 



