85 



by a similar replacement of the Cheribon variety. In Surinam the 

 banana known as Gros Michel, which was very liable to the so-called 

 Panama disease, has been replaced by the Congo variety which is not 

 susceptible, while the substitution of American vine-stocks for European 

 ones as a means of avoiding attack by Phylloxera, is perhaps the best 

 example of this method. Rotation of crops is one of the best means 

 of combating individual pests or groups of pests, and this has been well 

 exemplified in the cultivation of cotton in the United States, and has 

 proved of the greatest value in sugar and cassava plantations. The 

 removal of all local conditions likely to favour the growth and develop- 

 ment of fungi and injurious insects, the removal of old stumps and 

 roots on newly broken ground, the free admission of light and air, 

 and the avoidance of overcrowding have proved of the greatest benefit 

 in Hevea and cacao cultivation ; to these may be added the capture 

 of harmful insects whenever possible by hand, traps, lights or trap 

 crops. In recent years the biological methods of control by the 

 propagation and distribution of parasites and other enemies of insect 

 pests have assumed great importance. 



Among direct methods the most important are : — The disinfection 

 of seed and plants, the treatment of the plants themselves with fungi- 

 cides or insecticides and the disinfection of the soil. The methods 

 and materials employed in these measures are discussed and the 

 various forms of spray apparatus in use are described and figured. 

 The use of ammonia gas, potassium bicarbonate, carbon bisulphide, 

 carbolineum, chloride of lime, quick lime and formalin as soil 

 disinfectants is summarised, and some idea of the average cost of 

 material and appliances is given. 



Dammermann (K. W.). De Rijstboorderplaag op Java. [The rice- 

 borer pest in Java.] — Dept. Landbouw, Nijverheid en Handel. — 

 Mec?. Lab. voor Plantenziekten, Soerabaia, 1915, 70 pp., 7 plates. 

 [Received 16th December 1915.] 



The following summary of this paper is given by the author. 



At present, five species of rice-borers are known in Java, viz : — 

 Schoenobius bipunctifer, Wlk., Scirpophaga sericea, Snell., two species 

 of Chilo and Sesamia inferens, Wlk. The most serious pests of rice 

 are the two first named ; S. bipunctifer occurs throughout Java, while 

 S. sericea is principally found along the north coast and is more common 

 there than Schoenobius. Sesamia inferens generally prefers maize 

 to rice and is only abundant on upland rice. The rice-borers have 

 several parasites, one of which, Trichogrammatoidea nana, Zehnt., may 

 destroy up to 60 per cent, of the eggs. The loss of crop caused by 

 stem-borers may amount to 10 per cent, and in some years reaches 

 50 per cent. After the harvest, many borers remain in the dry stems. 

 When the rice is harvested at the close of the rainy season (April-May), 

 as is generally the case, and the fields lie fallow during the dry season, 

 the borers hide in the stumps, where they remain from May to October. 

 At the beginning of the next rainy season, the caterpillars pupate and 

 the moths emerge and lay their eggs on the seedbeds of the next 

 crop. The regions, which suffer most from borers are those where 

 many fields remain unprepared and unplanted during the dry season, 



