Insect Migrations in Tropical America. 159 



August, and on this occasion control was finally effected by 

 an unidentified egg parasite, the Tachinids being rare " 

 (St. Vincent Kept, of the Agricultural Department for 

 1915-16, p. 17). 



In 1919 S. C. Harland, who has studied the life-history 

 of the insect in St. Vincent, wrote to me as follows : " Cal- 

 podes was very abundant in St. Vincent for several months 

 in 1916, but never abundant at the Experimental Station 

 since. Apparently the eggs are parasitised as soon as laid. 

 I can find the eggs all the year round, but they don't seem 

 to hatch except at certain periods. This year, 1919, I 

 noticed attacks on the windward coast. I have never 

 seen any migration. I don't think that migration from 

 island to island comes into play at all. We have more of 

 its food-plant here than any other island, and it may be 

 possible that the mature insects fly northward." 



Harland is of the opinion that the sudden outbreaks are 

 due to temporary lack of parasites rather than to migra- 

 tion. We have, however, positive evidence of the migration 

 of this butterfly and, in spite of Mr. Harland's remarks, 

 I think that it will be found to be the explanation of many 

 of the outbreaks of the insect in the West Indies. The 

 rapid reduction of the outbreaks may be explauied by the 

 abundance of the parasites, but to explain the original 

 increase of the insect by a decrease in the parasites puts us 

 oidy one stage back in the inquiry. Doubtless the uimsual 

 hours of flight and the high speed attained has caused 

 many migrations to be overlooked, or, when seen, to be 

 confused with some other insect. 



Cydamon leilus. 



Cydanion leilus in Trinidad. 



The day-flying moth Cydamon (Urania) leilus is well 

 known for its migratory habits. Isolated records of its 

 migrations are scattered through entomological literature. 

 I have given below all the information that I have been 

 able to obtain with regard to its occurrence in Trinidad. 

 Some of the records have been published before, but mostly 

 in obscure local periodicals. The particulars for the years 

 1917, 1918, and 1919 are from my own observations. 



1868. II. (*aracciol() in the Journal of the Trinidad Field 

 Naturalists' Club, vol. i. (1892-1891), p. 16, says that 



