338 Mr. L. D. Cleare on 



on the food-plant Cleome polygama L., while Mr. H. W. B. 

 Moore has bred it on Cleome speciosa Kth., cabbage, mus- 

 tard, and horse-radish; all closely related plants. 



While this insect occurs in the county of Demerara it is 

 far more common in Berbice, where it can usually be seen, 

 and where its migrations only appear to take place ; in the 

 same way the CalUdryas are more or less confined to the 

 Demerara and Essequibo districts. 



Summary. 



It will be observed that three of the migrations of CalU- 

 dryas were from west to east. First the one observed by 

 Mr. Gainfort in 1912, then the one seen by Mr. Messervy 

 in 1916, and lastly, the one which I witnessed in March 

 1919. Mr. Wilhams points out in his paper that the general 

 direction of such migrations was from north-west to south- 

 east and vice versa, and the three migrations mentioned 

 above may be taken as agreeing with this in a general way. 

 He adds, however : " There is yet no record of a migration 

 in a north-east or south-westerly direction." The migration 

 observed by Mr. Winter at Mocco-mocco Point, Essequibo 

 River, in February 1914 was from east to west, practically 

 just the opposite direction to all previous records, and to 

 Mr. Williams' remark quoted above. 



. Mr. Wilhams also says : " Secondly, all migrations of 

 CalUdryas in which date is recorded took place between 

 May and October." The migration which I observed took 

 place on March 18th, while Mr. Winter observed one in 

 February 1914. 



A very interesting point which was brought out by Mr. 

 Winter's observations is that such migrations are of frequent 

 occurrence in the dry season. He says that the generally 

 accepted opinion is that such migrations precede dry weather. ^ 

 Again, the recent migration proved to be an exception, for 

 it occurred when the rainfall was above the normal for the 

 year, and this condition continued for some weeks after. 



Mr. Wilhams in his paper on the migration of Catopsilia 

 staUra suggests that the reason for these insects setthng 

 in patches on the ground is for the purpose of obtaining 

 nourishment in the form of salts from areas " where the 

 urine from animals passing along the road had recently 

 dried up." This theory would certainly not hold good 

 in at least three of the instances given here — Nos. 7, 8, and 

 9 — as in these places there are no such animals, while in the 



