256 THE entomologist's reoobd. 



he witnessed in June, 1867, at Hartlepool. He first observed an 

 unusual number of white butterflies in the street, about 9 a.m., and 

 their numbers steadily increased ; by noon they were flying in hundreds, 

 and at 2 p.m. there were thousands of them to be seen at once, all 

 flying in one direction, viz., from east to west. They continued to pass 

 in undiminished numbers till towards 5 o'clock, when a sudden 

 thunderstorm and very heavy rain came on. Such of the butterflies 

 as did not obtain shelter Avere quickly driven to the ground where they 

 were pelted to death by the rain, and floated in hundreds along the 

 flooded channels. When the rain ceased the day was too far advanced 

 for flight to be resumed, and next day, although there was a large 

 number about the streets, they flew in a desultory manner and entirely 

 without the steady purpose-like flight of the day before. Enquiry 

 elicited that fishermen had seen the flight coming in from the open sea 

 (where many had settled on the boats) which was perfectly smooth, 

 and one or two had noticed that they rested on the water and rising 

 again therefrom had pursued their flight. Robson calculated that the 

 denser portion of the column was about 100 yards wide, although 

 stragglers extended much further on either side. The length must 

 have been very great, for the butterflies continued to advance from 

 9 a.m. until 5 p.m., and had not commenced to decrease in numbers 

 when the storm dispersed them. Cordeaux reports {Entom., vii., p. 

 161) that on the morning of June 4th, 1874, " very large numbers of 

 Pieris hrassicae and P. rapae, the latter, however, very greatly pre- 

 dominating, came into the North Lincolnshire marshes from the 

 Yorkshire coast of the Humber (which, at this point, is from four and 

 a half to five miles across). For an hour that I was near the sea 

 embankment they were constantly passing inland, flying, too, against 

 a rather stiff south-west breeze. Looking towards the centre of the 

 river with a strong glass I could distinguish flights of them far away, 

 flickering in the blaze of sunlight against the grey background of water, 

 like falling snowflakes. I remember a very similar immigration of white 

 butterflies in the dry summer of 1870." Our own observation (wpra) 

 of the immigration of P. hrassicae between Dover and Deal, took place 

 in 1887, and the abundance of this species and P. rapac in the autumn 

 of that year in Britain was extraordinary. Barrett records {Ent. Mo. 

 Ahu/., xxiv., p. 85) that towards the end of May, 1887, when walking 

 along the top of the clifls from Hunstanton to Old Hunstanton he 

 came upon multitudes of P. hrassicae (and to a less extent P. rapac) 

 flying about the level ground on the top of the clifi', and settling in 

 dozens on the flowers, without appearing to be in any such numbers 

 inland. As there were no fields of cabbage, turnips, &c., in the 

 neighleourhood, he suspected that he had come upon a flight of 

 immigrants immediately after their arrival. Adkin gives (Proc. 8th. 

 Loud. Ent. Soc, 1899, p. 47) interesting details observed by himself 

 and his daughter on July 27th, 1899, between Eastbourne and Beachy 

 Head. On this morning, although white butterflies had not previously 

 been very common, he noticed great numbers of Pieris rapae, large in 

 size but poor in condition, fluttering over the furze on the upper part 

 of the slopes, for the whole length of the down, the butterflies being 

 left behind when the summit of the Head was reached. On returning 

 to Eastbourne his daughter remarked that she had during the morning- 

 seen large numbers of white butterflies all flying in from the sea, and 



