332 Mr. L. D. Cleare on 



other migrations, none of which have been recorded by 

 Mr. WilUams in his paper, or elsewhere, as far as I am aware. 

 The majority of the records would, I presume, refer to 

 Callidryas enbule L., the common sulphur-yellow butterfly 

 of the colony, but there is also a record of a migration of 

 Pieris phileta F., as well as one of Cat ops ilia statira Cram. 

 The localities and direction of these migrations are in 

 every case indicated on the accompanying map. The signs 

 used by Williams in recording a migration of Catopsilia 

 statira in a recent number of the Trans. Ent. Soc. (1919, 

 p. 76) have, for the sake of uniformity, been used in the 

 map illustrating this paper. 



Callidryas eubule L. 



1. About 1.45 p.m. on March 18, 1919, Mr. A. Seton Milne, 

 Government Veterinary Surgeon, on his arrival at the office 

 drew my attention to the number of yellow butterflies 

 about. On looking out it was obvious that a migration 

 was taking place. No such migration was going on at 

 11.30 that morning. Mr. Milne informed me that he first 

 observed these insects about 1 p.m. in Croal Street. He 

 said that they were then more numerous than at the time 

 when I saw them. I immediately left for Croal Street to 

 make observations. The butterflies could be seen every- 

 where between this laboratory and Croal Street, a distance 

 of half-a-mile north, and as the insects were travelling in 

 an easterly direction the width of the swarm was at least that. 



At 1.55 p.m. I noted that the butterflies were not passing 

 in a continuous stream, but in twos and threes, and some- 

 times larger numbers. The direction of the flight was due 

 east, and they were usually between six and twenty feet 

 off the ground. 



From my point of observation I could look over a width 

 of about 120 yards, and the butterflies crossing this area 

 were counted. During the first minute of observation 

 thirty-three insects crossed. After that the count was made 

 every five minutes. The results were as follows : — 



1st 5 minutes 100 butterflies passed — 20-0 per minute. 



2nd „ 95 ., ., = 19-0 



3rd „ 40 „ „ =: 8-0 



4th „ 63 „ „ = 12-6 



This works out at an average of 14' 9 butterflies passing 

 every minute. 



