THE MIGRATIONS OF BUTTERFi.IES. 1079 



flew singly, and never crowiled into swarms. Most of tliese butterflies passed over 

 our streets at too great a lioiglit to permit close inspection — a few alighting here and 

 there on lamp-posts, sign-boards, or in tlic more rural parts on flowers. It was from 

 these that I obtained the specimens in my collection. They nearly all looked worn 

 and shattered, and there were no fresh specimens among tliem : clearly indicating that 

 they were not raised in the neighborhood of the city, but had come from distant parts. 

 On the 18th some of the stragglers were still to be seen, but on the 19th tlicy had all disap- 

 peared. The second migration took place last fall [18G3], but did not reach San Fran- 

 cisco. ... By comparing notes received from Mr. .Johnson, of Marin County, I have come 

 to the conclusion that the country to the northward crowded with this Vanessa, must 

 have sent at least one colony south; and I was told by the above-mentioned gentleman, 

 the statement being contlrmed by several intelligent farmers of the same neighborhood, 

 that large numbei'S of a brown butterfly had come from San Quentin, and crossed over 

 that part of tlio bay which stretclies between San Rafael and Saucelito. About the same 

 time, great numbers of the same insect were observed in Lagunita Valley, at the 

 base of Tamal Pais, where the swarms gathered in a great crowd, and disappeared as 

 suddenly as they came. (Proc. Cal. acad. nat. sc., lii: 124.) 



Perhaps, however, the most striking; instance in modern times, because 

 noticed and recorded by so many persons, is the invasion of Europe by great 

 swarms of Vanessa cardui during tlie summer of 1879. They were first 

 observed at the end of May at two points considerably distant from each 

 other. Ritter says that he was near Nikolsburg in Moravia on a liot 

 sunny day at the end of May by the edge of a forest, when at about two 

 o'clock in the afternoon, he noticed a peculiar humming sound. "Imme- 

 diately," says he, "I observed an enormous flight of butterflies which came 

 in a westerly direction over an open forest park and pitched as by com- 

 mand on the sunny wall opposite me." He hurried oft' to find others to 

 witness the sight, but on his return in five minutes, foimd only one or two 

 individuals instead of the many tiiousands he had left there. The other 

 observation was much farther to the south. Ninni has collected the facts 

 regarding this swarm, which appeared at Treviso north of Venice between 

 the 30th of May and 6th of June. On the 30th, he says, there were 

 comparatively few butterflies, all passing in a northwest direction. On the 

 3l8t the same, the wind at this time coming mostly from the north. On the 

 Ist of June with wind mostly west of north, they moved in a direction to the 

 east of north, and this direction they retained for the three following 

 days. On the 2d they came in immense numbers, flying from 5.15 a.m. 

 till sunset, the wind varying on cither side of north. On the 3d the 

 numbers were still great but began to decrease, with the prevailing wind 

 from the north-east, so that they were flying directly against the wind, 

 which had now attained a greater strength. On the 4th, with the wind 

 more in a southerly direction, they moved in the same direction as before 

 but were only remarked at certain points. On the 5th, with the wind in 

 an easterly direction, the numbers were about as on the previous day, 

 while on the f5th with the prevailing wind from the north-east, the 

 flight only began at 1 o'clock in the afternoon and lasted for an hour and 

 a half. 



