531 



in fact by many, such remedies are considered more valuable than 

 spraying. It would be a great advantage if certain thrips- infested 

 areas of cacao could be kept under observation for a period of years 

 and experiments made to comj^are the value of certain cultural methods 

 and of spraying. 



Weather conditions appear to have a considerable influence on the 

 abundance of thrips. If during the normally dry season (February to 

 May or June) there are frequent showers, thrips are likely to be more 

 numerous ; the reason for this is not definitely known. The processes of 

 draining, bedding, forking and the use of mulches and manures are 

 discussed. It is suggested that in certain localities where drainage is 

 ample and yet thrips persist, a few, perhaj^s one in four, of these drains 

 should be filled in by making a layer of stones 6 to 8 in. deep at the 

 bottom and then filling up to the ground level with leaves, bush, 

 manure, and any organic matter that would rot and assist the growth 

 of the roots. These would continue their function as drains for some 

 time, and before they became useless as drains the trees should have 

 made such vigorous growth and increased their yield sufficiently to pay 

 for the construction of new drains if necessary. On estates where the 

 soil is thin a constant cover of mulch should be maintained, composed 

 of any organic matter and laid perhaps half knee deep. 



The cacao beetle [Stirastoma depressum, L.] is confined almost 

 entirely to the leeward side of the Island. It is suggested that trapping 

 the beetles, which has proved successful in Trinidad [see this Review, 

 Ser. A. i, p. 122, etc.]. should be more generally practised. The mealy 

 bug [Pseudococcus cifri] and the black or acrobat ant [Cremastogaster 

 sp.] are still prevalent in some localities [see this Review, Ser. A, iii, 

 p. 583] ; for the former, a wash containing 5 lb. Scalo and | lb. Blackleaf 

 10 to 100 gals, water is a satisfactory insecticide, and should also be 

 effective against the ants, provided that all the nests on the trees are 

 exposed before spraying. 



Williams (C. B.). Sugar-Cane Varieties and Froghopper Blight in 



Trinidad. — Bull Depf. Jgric. Trinidad and Tobago, Port-oJ-Spain, 

 xviii, no. 2, 8th September 1919, pp. 70-83. 



The different varieties of sugar-cane grown in Trinidad are discussed 

 as regards their relative immunity to frog- hopper blight. Although 

 no variety was found to be totally immune, resistance varies 

 considerably and is also influenced by the soil and climatic conditions. 



Urich (F. W.). Control of the Cacao Thrips in Trinidad and Tobago. — 

 BidL Dcpf. Agric. Trinidad and Tobago. Port-oJ-Spain, xviii, no. 2, 

 8th September 1919, pp. 8^97, 16 figs. 



A popular description is given of the life-history, damage by and 

 remedial measures against the cacao thrips [Helioihrips rubrocinctu^]. 

 The bulk of the information given has been noticed elsewhere [see this 

 Rerieiv, Ser. A, vi. p. 496, etc.]. 



