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Wednesday, October 16th, 1912. [xcvii 



Occasional migration die to bxcessh b drought as a cause 

 scviii 1 



OF THE SPREAD OF BUTTERFLIES INTO NEW LOCALITIES. — Professor 



Poulton brought forward the following note on behalf of the 

 Rev. K. St. Auhyn Rogers, and exhibited the two Libylhea and 

 the five Axterope (Crenis) therein mentioned : — 



"The migration of butterflies is a subject of perennial 

 interest and one on which many more observations are needed. 

 It may perhaps be worth while to record a migration which 

 took place at Rabai during the early part of 1911. 



••The first species to be observed was Catopsilia flordla, a 

 species which is one of the best known migrants. The date 

 on which the migration was first observed was March 12th, 

 and it continued for some three weeks. At no time during 

 this period were the migrants conspicuous for their large 

 numbers, hut every specimen of C. floreUa seen, appeared to 

 have important business to the north, which urged it to keep 

 moving steadily in that direction. 



'' Towards the end of this period I noticed that there were 

 other butterflies joining in the movement, and on March 31st, 

 I spent an hour in my garden capturing these. I found that 

 Atelhx phalantha and the skipper Andronymus neander, the 

 latter also previously recorded as a migrant, were represented 

 in some numbers. However, the most interesting butterflies 

 seen, as tar as I was concerned, were Libythea laius } Trim., 

 and Asterope (Crenis) natalensis, Boisd. Of these I captured 

 two of the former and live of the latter in about an hour, and, 

 as they were living fast and high, it 18 evident that they must 

 have been present in considerable cumbers The two species 

 resemble one another on the wing, and when travelling fast 

 are not easy to discriminate, but I am under die Impression 

 that the Asb'i'ojM was proportionately more numerous than 

 these figures would indicate. Now it is worth observing that 

 neither of these species is common in the coast district of 

 British Mast Africa, and I had not seen the Libythea since 

 1899, after a period of very prolonged and severe drought — 

 conditions which were present, although to a lesser degree, in 



