516 



unfortunately prohibits their use except in special cases and in small 

 areas. The discovery of some less costly procedure, which could be 

 applied on a larger scale and to many kinds of crops, would be of 

 great advantage in the campaign for plant protection. 



Thill ARD (R.). La Culture du Tabac de Sumatra au Cameroun. — 



Agron. Colon., Paris, vi, no. 43, July 1921, pp. 23-40, 3 figs. 



Tobacco that has been fermented and is waiting in the yards for 

 sorting, classification and packing, is liable to attack by insects, of which 

 the chief is [? Lasioderma serricorne]. This species multiplies very 

 rapidl}^ devouring the leaves and causing much damage, sometimes 

 riddling the bundles through and through. The eggs are laid between 

 the leaves, and the larvae pupate in cocoons. Infestation is generally 

 worst in the dr}^ season. Another pest [probably Dermesies lardarius] 

 causes very similar damage. Both of these beetles occur generally 

 in tobacco heaps that are not sufficiently fermented and of which the 

 temperature is less than 50° C. To prevent damage the heaps should be 

 isolated, and each year, after the tobacco has been cleared away, the 

 floors where fermentation has taken place should be washed down with 

 boiling water or copper sulphate. WTien infestation is discovered, it 

 is a good plan to remove all the tobacco, so that the floor and walls may 

 be thoroughly cleaned, and it should not be put back until all the insects 

 have disappeared. In the case of small quantities only, tobacco 

 should be enclosed in hermetically sealed cases and fumigated v/ith 

 sulphur ; the same method may be used in the store-yards if great care 

 is taken. Other preventive measures include washing the floors with 

 paraffin and water, whitewashing the walls with lime, and removing 

 all tobacco debris from the yards each year. 



Ballou (H. a.). Report on a Visit to Grenada. — Agric. News, Bar- 

 bados, XX, no. 503, 6th August 1921, pp. 250-251. 



A visit was made to Grenada in April-May 1921 to investigate the 

 damage by black ants and mealy-bugs in the cacao plantations and to 

 consider remedial measures. The most abundant mealy-bug is Pseudo- 

 coccus citri, which occurs on the leaves, pods and flower-cushions, and 

 the leaves and bark of suckers. The chief damage seems to be to the 

 pods and flower-cushions ; some trees produce abnormally large cushions 

 bearing numbers of flowers, but producing very few pods, apparently 

 as a result of mealy-bug attack. Black ants are present in numbers, 

 both where mealy-bugs occur and where they do not. Tests have been 

 made of spra^ang against both of these pests, and the results will be 

 reported later. The most satisfactory remedy for black ants consists 

 of the removal of nesting places on the trees ; thorough cleaning of 

 the trees, treatment of old wounds, and removal of hiding-places, 

 together with sprays for mealy-bugs, should result in satisfactory 

 control. During the last few years a large termite has been attacking 

 cacao in Grenada, fomiing a nest or colon}^ that has no 

 connection with another on the ground or in another tree, and 

 constructing no covered galleries in which to travel from place to place. 

 The insects invade the trees through wounds, where decay has started, 

 and penetrate into healthy tissue, often causing severe damage. Attack 

 is seldom serious except in neglected plantations, and the remedy lies 



