( xcviii ) 



OF THE SPREAD OF BUTTERFLIES INTO NEW LOCALITIES. — ProfeSSOr 



PoULTON brought forward the following note on behalf of the 

 Eev. K. St. Aubyn Rogers, and exhibited the two Lihythea and 

 the five Asterope {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 migra- 

 tion which took place at Rabai during the early part of 1911. 



" The first species to be observed was Cat02)silia florella, 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, but every specimen of C. florella 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 

 Atella phalantha and the skipper Andronymus neancler, the 

 latter also previously recorded as a migrant, were represented 

 in some numbers. However, the most interesting butterflies 

 seen, as far as I was concerned, were Lihythea laius. Trim., 

 and Asterope {Crenis) nataleiisis, Boisd. Of these I captured 

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

 as they were flying fast and high, it is evident that they must 

 have been present in considerable numbers. The two species 

 resemble one another on the wing, and when travelling fast 

 are not easy to discriminate, but I am under the impression 

 that the Asterope 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 East Africa, and I had not seen the Lihythea since 

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

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

 1911. The Asterope I had only once previously taken in the 

 district, although I think I saw it on another occasion. I 

 have twice taken the Asterope in 1911, since March 31st, and 

 have seen others, and I have also seen what I took to be a 



