152 FROOHOPPER BLIGHT OF SUGAR-CANE. 



round, seldom exceeding half an inch in diameter. In the Mosaic 

 Disease, recently discovered in Trinidad, the leaf is irregularly mottled 

 with indistinct streaks which are pale from the first and never become 

 darker tlian the healthy leaf. (p. 27). 



HISTORY OF THE BLIGHT. 



Elif.'l)t, apparently similar to the present one, was recorded in 1862, 

 1869, lb78, and various years up to 1889 when the froghopper was first 

 recognised as the probable cause. From about 1890 onwards for several 

 years, the gradual degeneration of the Bourbon cane was taking place, 

 largely due to Red Rot (ColIetotricJmm). No outstanding attacks 

 appear to have occurred again until 1906, although a few slight local 

 outbreaks are recorded in 1900. (p. 30). 



In 1906 commenced a series of severe attacks which has continued 

 with occasional irrtei'vals up to the present time. The relative severity 

 of blight in these years is shown in fig. 7, which indicates a recurrence 

 of periods of severer blight at intervals of four or five years. The times 

 of greatest damage were 1906-8, 1911-1912 and 1917-18. (p. 32). 



The weather conditions for each year from 1906-1919 are summarised 

 on Table I. (p. 83). 



FROGHOPPERS IN OTHER COUNTRIES. 



Tobago has its owrr species of froghopper, Toinaspis carmodyi, which 

 however has done no damage, (p. 43). 



In Grenada the Trinidad insect is known and in 1916 did severe 

 damage in a few small areas, (p. 44). 



From St. Vincent there is a single specimen of the Trinidad frog- 

 hopper, in the collection of the British Museum, captured about 1890, 

 but in December 1917 I made a close search in the southern half of the 

 island and failed to find any. (p. 44). 



No froghoppers have ever been found in Barbados, St. Lucia, 

 Martinique, or the nrore northerly Lesser Antilles, Dominica has one 

 species, Tomasjns dominicana, of which the habits arexmknown. (p. 44). 



In Cuba pastures and occasionally cane fields have been damaged by 

 Tomaspis bicincta. In 1916 the loss due to damaged pastures in the 

 province of Caminguey was about i64,000. (p. 45). 



No damage has been reported from Jamaica, but several species of 

 froghoppers are known to occur there, (p. 46). 



In Surinam Toniasjns tristis occasionally damages the caires. The 

 nymphs are ^not root feeders bvit are found two or three feet above the 

 •ground on the cane and bases of the leaves, (p. 46). 



Iir British Guiana Tomasfis flavilatera was known as a minor pest 

 from 1909 to 1917 but the harm done was negligible. In 1918 however 

 an extensive outbreak occurred in three difi'erent localities and severe 

 damage was recorded. It is believed to have been related to certain 

 climatic and soil conditions, (p. 47). 



In Colombia Tomaspis hogoiensis has for some years been recorded 

 as danraging pastures, (p. 48j. 



In Panama Tomaspis lepidior has been mentioned as damaging cane 

 and grass, but apparently to no great extent. A froghopper of the genus 

 Clastoptera was found destroying the flowers of Cacao, (p. 48). 



In British Honduras damage was reported to sugar-cane by a frog- 

 hopper in 1883, but no recent particulars are available, (p. 49). 



In Mexico cane and pastures have been damaged for many years 

 jpast by Tomaspis postica. (p. 49). 



