86 



iDecause water for irrigation is not available. When two crops of rice 

 are grown in succession, the second crop may be infested by the 

 offspring of the borers of the preceding one, but if the fields are care- 

 fully cultivated and harvested regularly, the damage is less serious. 

 The pest is most efficiently checked by crop rotation, using a crop 

 on which borers cannot feed. The insects are most abundant after 

 very dry seasons followed by late rainy ones. All varieties of rice are 

 liable to the attacks of borers, nor do varieties appear to exist which 

 are obviously preferred by borers. In some districts, however, the 

 bearded varieties are more seriously infested than the non-bearded 

 types. Weak varieties which stool badly, are more damaged by these 

 insects than others The most effective method of control of this 

 pest is to destroy the borers, which remain in the stubbles after the 

 harvest. Deep ploughing immediately after the crop is reaped, is the 

 best remedy ; if this is impracticable, as in many non-irrigated 

 districts, burning the stubbles is advised and good results were 

 obtained by this method. It is not advisable to grow two or more 

 crops of rice in succession, unless large areas can be prepared and 

 reaped at the same time. Another important measure is to kill the 

 first brood of the borers ; the egg-clusters on the seed-beds should be 

 collected by children and the seed-beds should therefore be arranged 

 in rows 40 inches wide. Collection of the egg-clusters should begin 

 when the plants are one week old and should be repeated every five 

 days. Infested seedlings should not be transplanted, but should be 

 removed and burnt or buried the same day. Light traps may be put 

 near the seed-beds to capture the moths. Ordinary kerosene lamps 

 placed in the centre of a tray containing water with a film of kerosene 

 or other oil are most useful ; they should be sheltered against rain. 

 The best results were obtained with an apparatus consisting of a wooden 

 framework, the sides of which are covered with cheesecloth, leaving 

 free only narrow slits, above which are fastened strips of wire gauze, 

 which slant downwards. The bottom of the case contains the tray 

 with water and oil, the lamp being placed inside. By this method 

 more moths are attracted, and of these only a few escape. By dis- 

 tributing large coloured engravings and pamphlets in Dutch and 

 Malay, the natives and others are being made acquainted with the 

 life-history of these borers and the methods of controlling them. 



IsHiDA (M.). Onderzoekingen over boorders en boorderparasieten in 

 het suikerriet van de Cultuurafdeeling van het Proefstation te 

 Pasoeroean. [Investigations on borers and borer-parasites in the 

 sugar-cane of the Experiment Station in Pasoeroean.] — Med. 

 Proefstation Java-SuiJcerindustrie, Soerabaia, pt. v, no. 12, 1915, 

 17 pp. [Received 16th December 1915.] 



The materials for these investigations on sugar-cane borers and their 

 parasites included eggs of Diatraea striatalis collected under natural 

 conditions, and of 5,068 egg-masses examined from 30th January to 

 5th March, 37 "6 per cent, were found to be free. This percentage was 



