THE ABUNDANCE OF WHITE BUTTERFLIES IN 1917. 37 



This year a similar phenomenon bas occurred, and apparently 

 under very similar meterological conditions, for, although we 

 had a good deal of rain in the late autumn of last year, the 

 winter was fairly dry, certainly colder than usual, and unduly 

 prolonged, and the weather of the latter part of July, when the 

 great abundance occurred, was tbe warmest of the j'ear, the 

 winds generally light in force and often from an easterly or 

 southerly quarter. It is not, however, my present intention to 

 enter into a detailed comparison of the two phenomena ; far more 

 exact information than is so far available would be necessary for 

 any satisfactory result in that direction ; but rather to put on 

 record sundry, possibly more or less disjointed, observations, 

 chiefly in regard to what has come under my notice in this 

 district (Eastbourne, Sussex). 



"Whites " were somewhat later than usual in putting in an 

 appearance in spring, the first P. rapce being seen on April 29th, 

 and P. brassicce was not noted until May 20th, but from that 

 time they continued throughout the summer, there apparently 

 being no distinct break between the spring and summer broods. 

 In point of numbers the spring emergence of all three species 

 of our " whites " was well up to the average, but it was not until 

 the middle of July that they were noticed to be in excessive 

 numbers. No doubt the summer broods were then just emerging, 

 and it was evident that they had fared well. 



On July 14th, on a journey by rail to London and back, I 

 could not help noticing the numbers of " whites " along the 

 railway banks, more particularly towards the Eastbourne end 

 of the journey. On the following day I had an opportunity of 

 observing them more closely as they flitted about the parades 

 and gardens, and, so far as I could see, they were all P. rapa- 

 and P. napi. A week later the total numbers had increased 

 considerably, and included a good many P. hrassica. At this 

 time one would have said that "whites" were more abundant 

 than usual, but it was nothing compared to what followed. 



On July 22ud, an almost windless day — what little movement 

 in the air there may have been was from but little west of south 

 — we sat in the garden for some hours during the afternoon, and 

 during the whole time white butterflies in large numbers were 

 continually passing over in one direction, viz. from the coast, 

 which is some 300 yards to the south-east of us, to inland, but 

 as houses are almost continuous from the coast, no doubt the 

 air currents over the garden would be exactly in the direction in 

 which the butterflies were flying. Some were flying high in the 

 air over the house tops and the tallest trees, while others barely 

 cleared the garden walls and even loitered in the garden. Of 

 these latter the majority were P. rapa, but both P. napi and 

 P. hrassicce were present. Later in the afternoon I went out into 

 the road at the other side of the house ; here they were equally 



