148 



an interval of seven or eight days, never more than ten, was allowed 

 between the applications. This comparatively short interval was. 

 made possible by the great immunising power of the covering film, 

 especially that left by the second application, which prevented attacks 

 "by larvae from the few surviving adults. It is most important that 

 the spray should not be stinted, as a uniform coating is the object 

 aimed at. The spray -nozzle should be at an angle of 45° to the rod. 



This method of control was found to be cheap : 22 gals, of con- 

 centrated polysulphide of calcium solution cost about 3s. lOd., the 

 requisite paste — containing 73 lb. of wheat flour — costing 65. Qd. (includ- 

 ing Is. Id. for fuel and labour). Twenty-two gallons of concentrated 

 spray therefore cost 10s. id. and yielded 367 gallons of 6 per cent, 

 spray, a quantity sufficient for one application to 333 eight-year-old 

 trees about 8 feet high and 7 feet in diameter. At the rate of about 

 2.S. per diem, the necessary labour for one application to 333 trees 

 (40 per diem) cost about 16?. 6d., so that the total cost for one 

 application per tree was under Id. This method would seem to 

 replace with advantage that of fumigation with hydrocyanic acid gas. 



MacMillan (H. F.). a Handbook of Tropical Gardening and Planting 

 with special reference to Ceylon. Second Edition, 1914, Colombo, 

 H. W. Cave & Co., x+662-f xxxv pp., 264 figi. Price 13s. id. 



Detailed information as to the trees and plants grown in tropic^,! 

 countries, and as to the methods of cultivation adopted, is of great 

 value to economic entomologists, as it facilitates an understanding 

 of the conditions under which insect pests occur. This work, though 

 primarily dealing with Ceylon, contains a great mass of information 

 on this subject very difficult to obtain elsewhere without reference to 

 a large number of books. The scientific and local names of plants are 

 given with all necessary details as to cultivation, while the chapters on 

 the standard and economic products of Ceylon are full of interesting 

 information. The 13 pages devoted to insect pests and preventive 

 or remedial measures are unfortunately not of the same standard as 

 the rest of the book. The tabular list of pests, which occupies more 

 than four pages, is so full of typographical errors as to render many 

 of the insect names unrecognisable. Among the remedies, arsenate of 

 lead is described as sugar of lead (lead acetate) and the information 

 given under this head is exceedingly scanty and incomplete, and it is 

 to be hoped that in any future edition of this otherwise excellent book 

 this section will be thoroughly revised and extended. 



CoPELAND (E. B.). The Coconut. London, MacMillan & Co., 1914, 

 xiv + 212 pp., 23 plates, price 10s. net. 



Regarded on botanical grounds as of tropical American origin, the 

 cultivation of the coconut has now spread over the tropical regions of 

 the whole world, and in many small islands it is a crop of the first 

 importance. A reliable book on the whole subject is therefore valuable, 

 especially as the author devotes one-third of his pages to a careful 

 discussion of diseases and pests of this palm. 



Perhaps the most serious of the diseases affecting the coconut 

 are those due to fungi. The most dangerous of these is the 



