MIGRATION AND DISPERS.VL OF INSECTS : LEPIDOPTERA. 155 



which floated on the surface of the water, and, for days afterwards, 

 they were to be seen driftmg into the various bays in the island of 

 Corfu." It was assumed, as they appeared to be taking the direction 

 of the coast of Italy, that they would, in all probability, strike the land 

 in the vicinity of Otranto. 



Scigliana observed a great flight at Trapani in 1837 ; these flew in 

 a direction from south to north. Lyell, Coni, Kaconi, Ghiliana, Mina- 

 Palumbo, and other Italian lepidopterists have recorded similar 

 immigrations. In 1873, Failla-Tedaldi first observed one of these 

 flights, but during April, 1878, this entomologist witnessed a tremendous 

 immigration of this species into Sicily. It commenced on the 2Gth, 

 was renewed on the 28th, and Avent on until May 8th. The insects 

 proceeded in serried columns, formed of "milliers" of specimens; each 

 column had a front of four kilometres or more ; in Cantelbuono, where 

 the streets barred their way they ascended vertically, retook their 

 normal direction, which appeared to be directed from the north to the 

 south ; the flight was observed in the neighbouring districts. During 

 this time, the Scolymxs and other plants in flower were covered with 

 hundreds of butterflies, and some days afterwards the larvfe Avere 

 obtained in numbers on several different species of plants. The 

 observer notes that the greater part of the specimens observed were, 

 worn, faded, and broken on the edges, and some of the examples were 

 extremely small ; the latter showed that the insects had been badly placed 

 (owing to their great numbers) for food, and the want of proper food- 

 plants on which to lay their eggs is suggested by Failla-Tedaldi as the 

 cause of their migration. The spring irruption was followed by an 

 immense number of newly emerged examples in July, evidently 

 descendants of the immigrants. 



The year 1879, will, however, long be remembered as that in which 

 one of the greatest and most general migrations of this species occurred. 

 A vast multitude of individuals moved from south to north over all the 

 countries of south-western, western and central Europe, and as the 

 main facts were collected at the time, a very fair general knowledge of 

 the extent of the migration and the area affected was obtained. The 

 swarm almost certainly came from north-west Africa, was observed at 

 Algiers as early as April 15th-20th, travelling in a north-easterly 

 direction. From April 26th- 30th, Crewe observed countless numbers 

 of the butterfly in the neighbourhood of Valencia and Barcelona, as 

 well as in Minorca, from May lst-8rd. Towards the end of May, the 

 main part of the swarm appears to have crossed into France, distributing 

 itself over the south-eastern districts of Switzerland and north Italy, 

 and, on the morning of June 5th, thousands of living specimens were 

 found on the snow at the hospice of St. Gothard. It then spread over 

 Germany and Austria, being recorded from various localities from June 

 7th-16tli. Another column appears to have crossed the Mediterranean 

 to Sicily, and spread itself over Italy during June. The more westerly 

 end of the swarm reached Strasburg as early as June 3rd-9th, Bisheim, 

 June 8th, Angers and Kennes, on June 10th, arriving on our southern 

 coasts about June 10th-13th, and spreading hence all over the country 

 into Scotland, whilst Belgium and the country directly north were also 

 inundated. There seems to have been many branch columns, although 

 the greatest possibly was that which passed along the Ehine valley, 

 where the larvae later destroyed the crops of artichokes and Artemisia. 



