84 FROGHOPPER lilJGHT OF SUGAR-CANE. 



Stevenson (1918) gives its natural distribution as Russia, France, 

 United States, Mexico, Trinidad, Hawaii, Porto Rico, Samoa, Philippine 

 Islands, Java, and Queensland, and says that it has been introduced 

 into Mauritius. Cuba and Argentine. 



To the natural distribution I can add British Guiana, Panama and 

 Grenada, and to the countries of introduction, Barbados and Colombia 

 should be added. From the high degree of humidity in the fields of 

 British Guiana it might have been expected to be common there, but 

 only a single infected specimen was seen during my visit in 1910. It is 

 possible that it is reduced by the continual heavy trade wind blowing 

 inland from the sea. 



It is also known to attack a large number of other insects, Coleoptera 

 (including Rhinoceros beetles attacking palms, and hard-back beetles), 

 Lepidopfera (including the grabs of the small Sugar-cane Moth-borers), 

 Ortlio'iiterd (including earwigs and cockroaches), Diptera (a sjjecies of 

 Stomoxijs is recorded by Kershaw) and Heniiytera (Reduviids, leaf- 

 hoppers and froghoppers). 



Urich (Bull. Dept. Agr. XI. p. 844) says that it did not attack the 

 Mexican bug (Reduviid) that he found feeding on froghoppers in Mexico, 

 but I found a Reduviid in Panama killed by it. 



From the Trinidad point of view the most important of these 

 alternative hosts are the caterpillars of the small Moth-borers of Sugar- 

 cane (Diatraea spp.) and the hard-back beetles. 



Practical Vne of the Fungus. The fungus under favourable conditions 



destroys such a large proportion of the froghoppers that attention was 



at an early stage drawn to the possibility of producing it artificially on 



.a large scale and introducing it into the cane fields in time for the early 



broods. 



It was previously known by experiments in Europe that, unlike m ;st 

 entomogenous fimgi, it would [grow well on artificial media, and Rorer 

 in 1909 and Gough in 1910 took up the problem of producing it in 

 quantity. Thej- both found that it produced abundant spores on potatoes, 

 yams, peas, rice, various artificial culture media such ai bouillon- igar, 

 and horse-dung agar and also on cylinders of sugar-cane. On the latter, 

 however. Gough (1911 C. p. 19) found that it grew but produced no spores. 



In 19J8 I a'tempted to cultivate it on '"filter-press cake", which is a 

 residue obtained in the manufacture of sugai', but found that on this 

 also it would grow slowly but produced no spores. 



Experiments along these lines r. suited in the making of large cabinets 

 about six feet high by about three feet square, designed by Rorer, in 

 which were a dozen or more trays of cooked rice which could be 

 sterilised and innocula'^ed with the green muscardine fungus. It is not 

 the purpose of the present rep irt to describe these in full (for this st-e 

 Rorer 1913 A. &. B.). From one of them about 80 lbs. of a mixture of 

 rice flour and spores could be produced and this was spread by various 

 methods in the field. 



The Usine St. Madeleine had in 1916 twelve of these cabinets in 

 operation and produced 1,230 lbs. of the spore mixture which they sold 

 to their subsidiary estates at 31 cents per lb. 



Distribution in the Field. The simplest, most laborious and least 

 wasteful method consists of catching adult froghoppers in tubes containing 

 spores and then allowing them to escape after sufficient time for infection. 

 The second method emphasized by Gough, consists of putting small 

 pieces of infected rice or potato in the upper axils of the leaves of the 

 canes in such a position that they would probably come into contact 

 with the adults. 



