1082 THE BUTTERFLIES OF NEW ENGLAND. 



wings. On the Ifith flights were observed again at Salzburg and at Ar- 

 mainvilliers. After this, observations are less frequent and important. 



This is by no means the only invasion that Europe has suffered at the 

 hands of Vanessa cardui ; a number of earlier instances are on record, 

 and almost all of them occurred at about the same time of year ; that is, 

 in the spring, before the time for the regular appearance of the indigenous 

 brood of the butterfly. The first of which I find any record is mentioned 

 by Cornelius as having taken place at Turin at the end of May, 1741. 

 Several subsequent flights have appeared in this immediate vicinity. Thus 

 De Loche saw a flight there in May, 1791, there was another at the 

 close of May in 1798, and Huber states that Bonelli saw one toward the 

 end of March, 1826, passing from the south toward the north ; apparently 

 this lasted several days, for it is stated tluit the butterflies were most 

 abundant on March 29. On April 20, 1851, Ghiliani saw a great flight 

 of these insects ; according to Bouquet, the day was fine, after continued 

 rain, and a strong breeze blew from the west ; beginning at 11 a. m., the 

 swarm came from the south-southeast and continued with a precipitate flight 

 for five hours towards the north-northwest. Again in 1857, when, accord- 

 ing to Cornelius, a flight occurred on April 26. All of these were in Pied- 

 mont. Huber gives an account of a flight seen by Wolf near Neucliatel, 

 on the 8th of June, 1826, which lasted at least two liours, the stream of 

 butterflies being from ten to fifteen feet broad. The same flight is recorded 

 June 8th, in the neighboring Canton Vaud at Granson, moving north- 

 ward, according to Cornelius, who further records a flight which passed 

 from London to the coasts of France in a south-easterly direction , in 1857, 

 without specification of the month, and one which occurred in April and 

 May, the year not mentioned, at Montpellier, passing in a northerly direc- 

 tion and composed of both sexes. The only definite exception to the 

 universal occurrence of these flights in the spring is the statement, 

 recorded by Hagen, of a flight in Switzerland, when, on October 26, 1827, 

 Prevost saw such a moving swarm, composed of a stream of butterflies, 

 from ten to fifteen feet broad, passing from south to north for two hours. 



Among the Euploeinae similar migrations are well known. Thus 

 Thwaites says in Moore's Lepidoptera of Ceylon : — 



On a fine sunny day, when calm or nearly so, amazing numbers of one or more 

 species of Euploea may often be observed wending their way in one direction, as if 

 floating upon the air a few feet from the ground, with an apparently sluggish move- 

 ment of their wings, though really making rapid progress. Resembling an army in 

 scattered open columns, they move on instinctively, regularly and simultaneously, as if 

 animated by a true migratory impulse. They naturally suggest a most interesting 

 inquiry as to whence tliese immense numbers come, and whither they are tending, 

 whether their course is a straight-ahead one, or is following a horizontal circular 

 direction of greater or less diameter. These insects when thus moving in company 

 show an unwillingness to be diverted from their course, and when attracted Iw a favour- 

 ite plant in flower, it is only for a few minutes that they remain upon it, and after 



