1 62 Journal of Agricultural Research voi.xvi, no. e 



been acting upon the advice of the Bureau of Entomology in efforts to 

 prevent injury, but the problem is greatly complicated at Miami Beach 

 by large areas of heavily infested red mangrove trees in near-by swamps. 



In 1916 and 1917, at Miami Beach, badly infested young casuarina 

 trees were removed or topped, and borers were killed in the pupal cells by 

 cutting them out. Some trees were sprayed with poisoned kerosene 

 emulsion. Supporting stakes of red mdngrove were removed. In 191 7 

 the infestation appeared to have been reduced, but in 1918 it was again 

 severe. In the red mangrove swamps there appeared to be a steady 

 yearly increase of infestation. 



The infestation at Hobe Sound, the farthest north that C. tranqueharica 

 has yet been found, has not been so severe. The casuarina trees are 

 new (May, 191 8) about 5 years old and of large size. In May, 191 6, 

 when these trees were younger and the injury more severe, the trunks 

 were thoroughly and repeatedly sprayed with the poisoned kerosene emul- 

 sion. About 900 casuarina trees growing in avenues were sprayed at 

 a cost of approximately 10 cents per tree. As the old formula, used at 

 this time, contains a larger proportion of sodium arsenate than is neces- 

 sary, the cost per tree can be lowered. The outfit consisted of three men 

 and a team of mules to haul the standard orange-tree spray pump. 

 Almost any good spraying outfit, however, would answer the purpose of 

 spraying the trunks of small trees. 



In addition to spraying, the rough bark at the bases of trees at Hobe 

 Sound was scraped and the borers killed by cutting them out of the 

 pupal cells. The infestation of 191 6 was less and there was a still further 

 decrease in that of 191 7, after the use of the same control methods, 

 A few borers were still found in the tops of the casuarina trees in 191 8 

 but these have been cut out. The infestation in the low scrubby red 

 mangrove tree here is not and has not been heavy. 



METHODS RECOMMENDED FOR COMBATING THE INSECT 



Investigations have shown that many trees can be saved by carrying 

 out the following methods of control : All badly damaged casuarina 

 trees should be cut and burned between September and March to kill 

 the insects before they emerge. The trees may be entirely removed, 

 cut off near the ground, or merely topped so that they will sprout from 

 the stump and make new growth. Since the borer usually attacks the 

 young trees near the base, where there are rougher bark and more suit- 

 able places for egg laying, care should be exercised that no infested 

 stumps remain. Trees only slightly damaged and showing evidence, in 

 the rapidly healing wounds, of recovery should not be cut. The wounds 

 will soon heal, and as the trees grow will disappear. 



Casuarina trees between iK and 6 inches in diameter, growing in prox- 

 imity to mangrove swamps or near other infested casuarina trees, should 

 be examined carefully in September and March and the young larvae 



