A FROGHOPPER ON SUGAR-CANE IN BRITISH GUIANA. 167 



ground is loose and open, they descend lower ; usually however the great majority 

 are within three inches of the surface. The froth of Tomaspis fiavilatera closely 

 resembles that of T. saccharina in Trinidad. It is softer and less elastic than that 

 of T. pubescens, the only other froghopper found on grass in this district. 



Just before emergence the full-grown nymph frequently ascends a grass stem 

 to a height of from six to ten inches and there forms a frothy covering in which the 

 final moult takes place. In the early morning these elevated froth masses are often 

 seen, but it is only at this stage that the nymph is found away from the roots. This 

 distinguishes it in habits from the froghopper (Tomaspis tristis, E.) at present found 

 on sugar-cane in Surinam, which regularly forms its froth at a height of two to five 

 feet above ground level (Williams 1916). This latter species is known to occur 

 in British Guiana and might at any time be found on sugar-cane. 



The Adult. 



Tomaspis fiavilatera was described by Urich in 1914 (Bull. Ent. Research, v, p. 43) 

 from specimens taken in British G-uiana ; at present it is not known elsewhere. It 

 is dark brown in colour, with the fore wings semi-translucent. On the costa of each 

 fore wing is a light yellowish-brown streak from the base of the wing almost to the 

 apex. This species is quite different in the scheme of coloration from T. saccharina 

 and its various relatives in Central America, all of which have as a colour pattern 

 two more or less complete light transverse bands on a dark ground. In the minuter 

 structure, in the profile of the face, in the structure of the male genitalia and in habits, 

 it shows a very close relationship to this group of froghoppers and must be considered 

 as a member of the saccharina series with an aberrant colour pattern. 



Among a large number of specimens examined there is very little variation. The 

 only distinct form is one in which the eyes are bright red instead of the usual black. 

 This is rare and appears to be in a proportion of 1 : 1000, or less. A similar variety 

 occurs in other species which will be dealt with later. 



During the day-time the adults may be found in large numbers sitting on the short 

 succulent grass growing along the drainage trenches. They are found also in the 

 axils of the upper leaves of the cane plants, but they do not frequent this situation 

 so exclusively as is found to be the case with Tomaspis saccharina in Trinidad. 



In addition to sugar-cane almost any species of grass seems to be used as food by 

 T. fiavilatera. The following grasses on which nymphs were found have been 

 identified : — Cynodon dactyhn (Bermuda or Bahama grass), Cynodon sp., Stipa sp., 

 and Panicum lascum. Adults were also seen in the rice plantations sucking the 

 stems of rice. There is, however, not much danger of its becoming a pest of the 

 wet land rice, as conditions at the root of the rice are quite unsuitable for the nymphs. 



Natural Enemies. 



During the months of August and September the following natural enemies were 

 seen. Of these only the Syrphid fly (Salpingogaster nigra) had been previously 

 recorded as attacking T. fiavilatera. 



Egg Parasites. 

 (1) The Vermilion Parasite (Oligosita giraulti). Several specimens of this minute 

 Chalcid were obtained during September 1916 from grass containing froghopper 



