170 C. B. WILLIAMS. 



(14) The Mongoose. This animal, which is sometimes considered as indirectly 

 responsible for the abundance of the froghopper in Trinidad, has unfortunately 

 been introduced here also. It is however not common, the general reason given 

 for this being that the low level of the land causes any burrows that it makes to be 

 immediately filled with water. On one estate the manager informed me that the 

 mongoose had got over this difficulty by making its burrows in the mounds of earth 

 heaped up to form approaches to the small bridges over the canals. 



Although work at present being carried on in Trinidad shows that the mongoose 

 is much more insectivorous in its diet than was apparently ever suggested, yet there 

 is no doubt that on the whole it is an undesirable animal, and it is to be hoped that 

 steps will be taken to prevent it reaching the hinterland of the Colony, where it might 

 do very serious damage. 



Artificial Control. 



The means adopted for the control of this froghopper, previous to my visit, consisted 

 in flooding the land and hand-picking the nymphs. It has been mentioned above 

 that at Plantation Ogle in 1915 over 380,000 nymphs were collected. This was 

 done by the regular insect gang of the estate, which at normal times is employed 

 in collecting the grubs of the sugar-cane moth borers (Diatraea and Castnia). 

 Flooding may be done for a few days as a temporary control measure, but in some 



Fig. 3. Sweep-net for catching froghoppers ; explanation 

 in the text. 



cases an uncultivated field is kept under water for a year or eighteen months. This 

 treatment is found to have a beneficial effect on the soil, as well as preventing these 

 uncultivated areas from becoming breeding grounds for insect pests. 



As the adults were found so commonly sitting on the short grass in the drains, 

 I decided to see if they could not be caught on a large scale by the use of sweep-nets. 

 Several forms of net were tried, but the one described and figured was finally 

 adopted and proved extremely successful. 



The net (fig. 3) consisted of a bamboo handle (b) going right across a stout wire ring 

 (a), thus giving considerably increased strength to the ring, which was about one 

 foot in diameter. The bag, made of a light canvas, was double, the inner bag (c) 

 in the form of a funnel open at the end to allow the insects to get into the main bag, 

 but preventing their escape. The outer bag (d) was also not stitched across the 

 end but instead a piece of strong mosquito netting was inserted about two inches 

 from the end and fastened all round to the canvas. This piece of net was important 



