24 THE BUREAU OF SCIENCE 



d'Herelle during the past few months, in experiments against 

 locusts in various parts of the Philippines, but neither has been 

 effective in exterminating the insects. As early as 1905 recom- 

 mendations looking to the establishment of the present method 

 of combating this pest were made to the Executive Secretary 

 and the Director of Agriculture, and resulted in the present 

 laws with reference to the matter. 



23. Tobacco pests. — Tobacco is attacked in the field by the 

 tobacco worm and plant lice, and it has already been demon- 

 strated that hand picking is the only sure and cheap way of 

 combating the former of these pests while the latter may be 

 held in check or practically eradicated by spraying with a weak 

 kerosene emulsion which in no way injures the leaf. Data con- 

 cerning, and remedial measures which may be applied in various 

 tobacco factories in Manila for combating, the cigarette beetle 

 have been furnished. If these suggestions had been followed 

 during the past three years in the 19 factories in Manila, which 

 have an export trade, there would have been a net saving of 

 over ^=39,000 on the losses which occurred for cigars actually 

 destroyed in the factories alone, not considering the loss of stock 

 outside of the factory due to the same cause or to loss of trade 

 due to the shipment of infested stock. 



24. Cacao insects. — It has been shown that the most effectual 

 means of controlling cacao insects is that of clean culture in 

 the cacao orchards, together with the use of repellent substances 

 to keep away the borers liable to attack the trunk, and the 

 spraying of fruits and leaves for biting and sucking insects. 

 There is no place in these Islands so far as known where this 

 crop has been given even semiscientific attention, although it 

 is one of the most promising of the many crops. 



25. Rice insects. — In the field, rice is attacked seriously by four 

 different insects; namely, locusts, the rice army worm, the rice 

 stem borer, and the tiangao, an insect which sucks the milk 

 from the setting grain. It has been shown that these insects 

 have their regular times of development and that their ravages 

 can be lessened by changing the time of planting rice so as to 

 avoid having it in a condition of susceptibility when the insects 

 are at the stage when they attack. Some farmers have profited 

 by this procedure, but as this can only be brought about by 

 the use of irrigation general relief cannot be looked for until 

 irrigation is commonly practiced. 



Stored rice is subject to the attacks of weevils, and this can 

 be prevented by properly constructed receptacles. The weevils 



