A BUTTERFLY INJURIOUS TO COCONUT PALMS IN BRITISH GUIANA. 277 



probable that the force of the wind had much to do with their escape, although 

 solitary instances are on record of the butterflies having been observed in this 

 vicinity- 

 Amount of Damage Done. 



Palms that have been attacked arc " skeletonized." The caterpillars devour all 

 the green part of the leaves, leaving only the thick central midrib and the fine 

 lateral veins (PI. ix). They pass in this manner from leaf to leaf until the entire tree 

 becomes denuded. The attack may be so severe that the tree succumbs, this 

 having occurred in a large number of cases in Georgetown. 



In September, after the insects disappeared (for they went away as mysteriously 

 as they came), a count was made of the palms that had died from this attack of 

 Brassolis. In the whole town there were about 107 dead palms. It was estimated 

 that there were some 2,000 of these palms in the city, so that about 5 per cent, had 

 ■succumbed to the attack. 



We can get some idea of the financial loss caused through this insect by making 

 some simple calculations. The average age at which a tree begins to bear is about 

 five years, so we can replace any tree in that time, and taking the average return 

 -at $1 {is. 2d.) per tree per annum, this being the figure generally used, the loss on 

 107 trees is $535. To this we must add the loss from nineteen hundred trees for 

 ■eighteen months, the period taken by them to recover. At the same rate this would 

 4imount to $2,850.00, making a total of S3,385.00 (£705 4s. 2d.). This estimate is 

 for the city of Georgetown alone ; should the loss in the coconut districts, Mahaicony, 

 -etc., be taken at the same figure, the amount would probably be startling. 



Writing of the attack at Plantation Grove in 1905, Mr. Bartlett says, " The 

 greater number of the trees in the cultivation of 40 acres have had every portion 

 of the green part of their leaves devoured, and present the appearance of brown 

 iskeletons of trees." In the same report he goes on to say, " In Georgetown 

 I estimate that quite half of the various kinds of palms scattered about the city, 

 -excluding those growing in the Botanic Gardens, where I am glad to say the 

 caterpillars have not appeared, have been more or less injured by this pest, some to 

 such an extent that they have died." 



It is noticeable that in this attack too the palms in the Botanic Gardens entirely 

 •escaped. 



Natural Enemies. 



Fortunately this pest has many natural enemies. Many biids, particularly the 

 ■common Kiskadee (Pitangus sulphumtiis), feed on the adult insects, while both 

 the eggs and pupae are parasitised. Bartlett mentions having reared an egg-parasite, 

 but does not give the name. During this attack two species of egg-parasites were 

 •also reared and are at present being determined by Mr. A. A. Girault, through the 

 U.S. Bureau of Entomology. Recently (Jour. Bd. of Agric. B.G., vii, no. 1, 1913, 

 p. 50) the well-known parasite Chalcis annulata, F., has been obtained from the 

 pupa of this insect. 



