178 H. A. BALLOU. 



(2) The size of the nest or colony. The ant hves in very small colonies ; often 

 the nest is no more than the collection of a few workers, eggs, larvae, pupae, and one 

 or more egg-laying females, located under a leaf or bit of bark. The destruction of 

 nests or colonies, when they are so small, so numerous and so well protected, would 

 present enormous difficulty as a control measure. 



(3) Their method of feeding. This species of ant damages trees directly. The 

 ants get into cuts made by pruning and into wounds made by boring insects, especially 

 when the bast and cambium are exposed, and they seem to feed there in such a manner 

 as to prevent these cuts and wounds from heahng over. 



(4) Their association with other insects. In nearly every instance where the 

 acrobat ant was noticed in cacao in Grenada it was associated with the mealy bug 

 (Pseudococcus citri), and in most cases where the mealy bug was seen the ant was also 

 present. I did not realise the possibility that these two insects were closely associated 

 until my visit was nearly over, so that I am not certain that this conclusion will be 

 borne out by more extended observation. 



The only remedial measures which seem practical at present have to do with better 

 pruning and care of the cacao trees, with a view to eliminating breeding places of the 

 ant as far as possible and to preventing the damage resulting from the feeding of the 

 ants on exposed cambium and bast tissues. The cacao tree would seem to be protected 

 from this ant by nature, since its hard, smooth bark offers very little opportunity for 

 its nests. Trees with a rough scaly bark, like mahogany for instance, are very suitable 

 for this purpose. In this connexion, I may say that while I saw on certain estates 

 evidences of excellent pruning methods and good care of trees, I also saw some cacao 

 trees where these matters were much neglected ; dead stubs, cavities of all sizes 

 resulting from borer attacks which had been neglected or badly treated, and from the 

 rotting out of cut stubs or broken branches, being much in evidence. Such con- 

 ditions are favourable to the ant, and all well directed effort toward better care of 

 the trees will have an effect in reducing the numbers of this insect. 



I should judge from what I saw that the cacao-planters want some dressing for 

 wounds made in pruning more efficient than anything they have at present. The 

 effects of good pruning are lost to some extent because the dressing used does not 

 protect the wood until it heals over, and the wood rots out ; cavities are thus produced 

 which tend to shorten the life of the tree. At the present time, lead paint, coal tar. 

 and resin oil to which tar is added to give colour, are the wound dressings used on 

 cacao trees. I am not able to recommend anything better, but experiments ought to 

 be undertaken with a view to finding some material which would give a greater pro- 

 tection to exposed surfaces of wood. In this connexion, trials might be made of 

 solignum, carbolineum, and similar wood preservatives. 



Black Blight. 



Black Blight is a fungus which does not attack the plant on which it grows. It 

 obtains its nutriment from the secretions of insects. Speaking generally it may be 

 stated that the only injury it causes to plants is that it cuts off a certain amount of 

 light from the leaves on which it occurs and thus interferes with their physiological 

 activities. 



