82 DISEASES 



the stored cobs and grain. Experiments instituted by the 

 writer with the object of discovering an inexpensive and 

 effective means of exterminating them resulted in the adop- 

 tion of the " Universal Ant Destroying Apparatus," in 

 preference to all other methods tested. This method of 

 exterminating rats might be applied with advantage in 

 cocoa plantations. The apparatus consists of an air- 

 pump connected by a length of rubber hose with a small 

 furnace. Glowing charcoal is placed in the latter, and 

 a spoonful or so of a mixture, comprising 85 per cent, 

 of white arsenic and 15 per cent, sulphur, is thrown 

 on the charcoal. When the pump is worked a current 

 of air is forced into the furnace. The air enters the 

 lower part of the furnace and drives out the poisonous 

 fumes, produced by the combustion of the powder, through 

 a hole near the top of the furnace, with which is connected 

 a second flexible tube. In practice the nose of the latter 

 is placed in the largest hole leading to the rat burrow and 

 the pump is started. As it is essential to restrict the 

 fumes to the burrow as much as possible it is necessary 

 before commencing operations to close up all other holes 

 leading to the burrow. Sometimes only one other is 

 found, but there may be as many as five. The amount 

 of fumes required for each burrow depends upon its size, 

 but sufficiency is indicated when they commence to issue 

 from the hole into which they were originally injected. 

 The pump should then be stopped and the hole plugged 

 up. Twenty-four hours later the burrow should be 

 inspected, and if any openings are found the burrow 

 should be treated again. Failure to destroy the rats 

 in the burrow by one application is usually due to the 

 insecure closing of the various bolt-holes. Should no 

 exits from the burrow have been made no further applica- 

 tion is necessary. 



INSECT PESTS 



The comparatively recent researches of the Entomo- 

 logists attached to the West Indian and Ceylon Botanical 

 Departments have furnished much valuable data in re- 

 gard to the insects destructive to cocoa in those countries, 

 and the writer is indebted to their reports for a great deal 

 of the following information on the subject. 



