52 TlilNlDAD AND TOBAGO BULLETIN. [XIX. 



SUGAE. 



SUMMARY OF A REPORT ON THE FROGHOPPER 

 BLIGHT OF SUGAR CANE IN TRINIDAD. 

 By C. B. Williams, M.A., 



Sugar Cane Entomologist. 



There has been published separately by the Department of Agricul- 

 ture a Report on the Froghopper Blight of Sugar Cane in Trinidad. The 

 summary of this report is printed below, as an outline of its contents 

 and the conclusions I'eached will be of interest to many people who would 

 find the complete report unnecessarily detailed. 



The Report is published as Memoir No. 1 of the Department of 

 Agriculture, is fully illustrated and may be obtained on application 

 at a price of 2,G. 



INTRODUCTION. 



The Sugar-cane cultivation of Trinidad covers an area of about 78 

 square miles, out of a total area of 1,750 for the island. The crop has 

 varied from 38,000 tons to 71,000 tons in the past twenty-one years. 

 The rainfall is about 64 inches, with a dry season from January to May 

 and a wet season from May to December. The crop is cut during 

 the dr^' season. Three or four crops are usually cut before replanting. 



The growing canes have been subject for many years to outbreaks 

 of a disease locally known as "Blight" or "Froghopper Blight," which 

 consists essentially of a browning and drying up of the leaves and a 

 check to the growth which may result in the total loss of the crop. 

 The loss during the past fifteen years has probably averaged £50,000 

 per annum and in 1917-1918 reached about £300,000. The insect 

 Tonasjiis saccharina. the sugar-cane froghopper, is almost invariably 

 found in abundance in the blighted fields, as well as various species of 

 root fungi, and both have been held responsible in \aiying degrees for 

 the damage. 



Conditions similar to the froghopper blight were reported in 1863, 

 but it was not until 1889 that the froghopper was discovered by 

 Hart and its connection with the damage suspected. In !I906 a 

 severe outbreak called attention to the subject once more and during 

 the next three years, all of which were characterised by severe blight, 

 various opinions were held as to the relative importance of the frog- 

 hopper and root disease. In 1909 regular investigation was started by 

 the Board of Agriculture and Rorer, Urich and Guppy studied the varied 

 aspects of the problem. The life history of the frogliopper was worked 

 out, two egg-parasites were found, and the green muscardine fungus 

 Avhich destroys the adult, was cultivated on a large scale. In 1910 and 

 1912 Gough and Kershaw continued the investigations. The former 

 discovered the Syrphid Fly, which destroys the nymphs, and the latter 

 reconnnended the search for a more efficient parasite outside Trinidad. 



During 1916 and 1917, I made a search for such parasites in British 

 •Guidna, Panama and Costa Rica. New froghoppers were found in all 

 these countries, but the enemies were found to be the same as those 

 already known in Trinidad. The range of the parasites is evidently 



