LEPIDOPTERA, ETC., AT SCOTTISH LIGHTHOUSES 61 



completely obscured the sun from the people on board the 

 Continental steamers, and the decks were strewn in all 

 directions with the insects (Tutt). Another account says, 

 " Every vessel that came into the harbour had the rigging 

 and deck completely covered with them, and the pier was 

 so thickly strewn with butterflies that you could not walk 

 without treading on them." 



Many similar immigrations of white butterflies such as 

 that at Hartlepool in June 1867, which lasted eight hours, 

 or that at the mouth of the Humber in June 1874, described 

 by Robson and Cordeaux respectively might be quoted, 

 but the above must suffice. One point, however, should 

 be mentioned, namely, that on several occasions, in calm 

 weather, numbers of the butterflies were observed to settle 

 on the sea, and, after a short rest, rise again and resume 

 their journey. It is further stated that a swarm on the 

 North Sea was accompanied by dragon-flies "which evidently 

 preyed upon them." 



In the course of its recent remarkable colonising career, 

 the famous " Milkweed " Butterfly of America, Danais {Anosia) 

 arc/i/ppus, must have made many long sea-flights, including 

 the 2000 miles passage from California to the Sandwich 

 Islands. For a series of years from 1876, it occurred with 

 some frequency on the coast of Europe, from England to 

 Gibraltar, Cornwall and Devon accounting for a goodly 

 number of the records. Examples, moreover, have been 

 taken in the Azores and the Canary Islands. Barrett {Brit. 

 Lepidopterd) considers that they reached us directly from the 

 other side of the Atlantic, by their own extraordinary power 

 of flight. Having seen numbers of D. arcliippus on the 

 wing there are now before me specimens which I captured 

 at Philadelphia, U.S.A., in July 1878 I can well believe 

 that if any butterfly is capable of such a journey, it is. Its 

 occurrence on the Atlantic far from land is vouched for by 

 the following records. In or about the year 1880, specimens 

 in King's collection were captured whilst flying about the 

 rigging of an outward bound vessel at a distance of from 200 

 to 300 miles from the western shores of Britain, and about 1 890 

 another was taken on board ship 60 miles from Cape 



