OBSERVATIONS ON INSECT PESTS IN GRENADA. 177 



live for about two months more, making a total of some 140 days. It contains also 

 an account of the use of the Chataigne Maron or Bread Nut {Pachira aquatica) for 

 trapping the beetle. This tree is a natural food-plant of the cacao beetle and is prob- 

 ably preferred by it to the cacao. The chataigne wood is cut into lengths suitable 

 for use in any of the several kinds of trap recommended. These are four in number :- - 

 (1) the heap trap consists of a heap of small branches two to four feet in length laid 

 on the ground ; the beetles are attracted to these heaps and lay their eggs there ; 

 the heaps should be burned or deeply buried at the end of six weeks ; (2) the suspended 

 trap consists of a bit of chataigne wood suspended by a wire among the branches of 

 the cacao tree ; (3) the leading trap consists of longer pieces of chataigne resting with 

 one end on the ground and the other between the branches at the fork ; (4) fork traps 

 consist in the use of small pieces of the chataigne placed between the branches at the 

 fork. All these traps have the same object, that is to provide an acceptable place 

 for the beetles to lay their eggs, and to be effective they must be renewed as soon as 

 they become dry. These bits of trap wood must be burned or deeply buried in order 

 to kill the grubs which hatch from the eggs. 



Spraying with arsenate of lead is also recommended in Trinidad, especially 

 in connexion with the use of the traps. The arsenate for this purpose is used at the 

 rate of 1 pound to 10 gallons of water. The poison should be well mixed to form a 

 smooth paste in a small quantity of water and then added to the full amount. It 

 should be applied with a powerful pump and fine nozzle, and the mixture in the spray 

 tank must be kept agitated all the time ; 50 gallons should spray 100 trees. In 

 spraying for beetle it is essential to cover the bark thoroughly from the collar (ground 

 level) up into the small branches. 



The Acrobat ant {Cremastogaster sp.). 



The only new insect which seems at present to threaten to become important as a 

 pest of cacao in Grenada is the acrobat ant. This insect, or pe^haps a closely related 

 species of the same genus, was described in the Agricultural News, Vol. xiii ,p. 298, 

 12th September 1914. It is a small, black or very dark brown ant, which lives on 

 trees and is characterised by its habit of turning up its abdomen over its back, as it 

 were. 



I noticed that it often occurs in great abundance on a small, well defined area, and 

 that at a distance of a few yards there are none to be found. I did not see many spots 

 in Grenada where the acrobat ant was actually doing much harm, but from wha^ I 

 did see and from what I know of the Barbados acrobat, I regard this insect as possessing 

 great possibihties of becoming a cacao pest in the future. I might venture so far as 

 to say that it seems to me possible that the acrobat ant may become the most serious 

 cacao pest in Grenada. Some of the features in the economy of this insect which 

 make this outcome seem possible are the following :— 



(1) The location of the nests. The nests of this species are formed in crevices of 

 the bark or wood of living trees, or in or upon dead trees, in fences, and out-buildings. 

 Broken or sphntered wood resulting from bad pruning, loose bark from the same cause, 

 a leaf which adheres to the surface of the bark, all these give nesting opportunities 

 to the acrobat ant, while the central pith in a cut branch, or the tunnels of boring 

 insects, are specially attractive to them for the purpose. 



