THE SUGAB-CANE FROGHOPPER IN GRENADA. 85 



The fields at Mount Home and Nainganfoix, on the contrary, were at an altitude 

 of 300-400 feet and each of them situated on a steep slope facing east and exposed 

 to the trade winds. The soil was a red volcanic ash earth, heavy when wet, but 

 rapidly drying to a crumbly mould. From the slope of the field alone there could 

 be no question of lack of drainage. 



It seems impossible to suggest any reason for the outbreak in these particular 

 fields. 



After a very close comparison of a number of specimens from Grenada with the 

 Trinidad species, I am unable to find any constant difference between them, either 

 in markings, profile or in the male genitalia. The Trinidad specimens (dead) usuaUy 

 have a bronze tint on the prothorax which is absent in all my Grenada specimens, 

 but as it is lacking also in some Trinidad specimens it cannot be considered as of 

 specific value. It may even be due to the method of killing. 



The specimens show the same range of variation in colour markings as the Trini- 

 dad species. There are two quite distinct forms, one with and one without a broad 

 V-shaped light brown mark at the base of the wings (when closed). 



At Mount Home a large number of sepcimens were captured and gave proportions 

 as follows : — 



With light 

 basal mark. Without mark. 



Males 32 36 



Females - . . 25 23 



57 59 



It will be seen that the two varieties are in almost equal numbers. The slight 

 excess of males is probably accidental and due to the method of capture. The 

 species must be considered as Tomaspis saccharina, Distant, and is in this case the 

 first certain record of this insect outside Trinidad. 



Several hundred spittle-masses were collected and examined, but no maggots 

 of the Trinidad Syrphid fly (Salpitigogaster nigra) were seen. If present, they must 

 have been too rare to be of any value as a control. At this season in Trinidad they 

 have generally become sufficiently numerous to exercise a considerable check on the 

 numbers of the froghopper. 



A single dead adult was found infested with the early white stage of the Green 

 Muscardine Fungus (Metarrhizium anisopliae). This also was much too rare to be 

 of any practical value. 



Attid spiders, an important control in Trinidad, were very scarce in the canes. 



A few sjjecimens of the predaceous grasshopper, Xiphidium fasciatum, de G. (which 

 is known to eat froghoppers) were found in the grass alongside the infested fields 

 and also in other localities in Grenada. It does not, however, appear actually to 

 enter the canes. It may on the other hand help to keep down the froghoppers in 

 the areas between and so prevent rapid spread. 



The mongoose, which is indirectly partly responsible for the depredations of 

 insect pests by destroying birds and 1 zards, is generally common in Grenada, and 

 in some localities rewards are offered for its destruction. 



