1900.] 225 



nowhere there were any of the Dragon-flies observed, that which 

 induces one to believe that the migratory swarm quitted its usual 

 habitation early in the morning, and immediately flew to a great 

 height. It was only on arriving near the earth that they flew against 

 the wind." 



[The rest of the paper is occupied by notes on former migra- 

 tions, in which the swarm of Vanessa carclui of 1879 is incidentally 

 alluded to, and in connection with which it is remarked that they 

 came to Belgium from England (!), an opinion that will meet with 

 but little favour here, in view of the carefully worked out history of 

 that migration. 



Then follow details, most carefully drawn up and collected to- 

 gether, of the swarms as observed at about thirty different localities, 

 almost each having some point of special interest, but which scarcely 

 seem of sufficient general importance to be reproduced here. But we 

 would remark on one point : several of the observers go out of their 

 way to say that the insects hit nobody ! ; and in one or two cases they 

 are accused of having bitten children and caused swellings, &c., thus 

 proving that the old superstition concerning these harmless insects is 

 not yet extinct. 



It is to be regretted that nowhere amongst the details are there 

 any data as to the proportions of the sexes in the migratory swarms. 



As to the causes of migration it seems to me that nothing certain 

 is known, perhaps never will be known. As a rule the multitudes are 

 so vast as to make it difficult to believe that all can have been bred 

 within a very limited area. On the contrary, it rather looks as if the 

 individuals in a certain initial locality being seized with an incon- 

 troUable migratory impulse were progressively joined by others till 

 the accumulations formed the ultimate swarm. And in this case it is 

 not necessary to suppose an ascent to any great altitude and subse- 

 quent descent therefrom. But this is pure speculation. 



Dragon-flies are notoriously sun-loving insects. But there is 

 reason to believe that when seized with the migratory impulse they 

 will fly by night and during heavy rain. On this point consult a note 

 published in the No. of this Magazine for November, 1896, in which 

 it is stated that examples of Pantala Jlavescens, F., entered the cabin 

 of a steamer in the Indian Ocean, nearly .300 miles from the nearest 

 land, at 11 p.m., during heavy rain. Such an occurrence as this is 

 pregnant with significance in connection with the whole subject of 

 migration, and tends to lend support to M. Lancaster's theory that 



