(dirphya pbinceps, JORD.). 2S1 



readies the stem, the control measure which I have recommended and which has 

 been successful in every ease, is to inject a few drops of carbon bisulphide or 



carbon tetrachloride into the tunnels of the borer. This operation is best carried 

 out by first sealing up all the exits of the horizontal tunnels in the stem with wet 

 clav. and then cutting- off the branch through which the insect entered the stem, 

 as close to the stem as possible ; this will expose a large hole through which a 

 few drops of the liquid can be conveniently injected, the hole being then sealed 

 up with wet elay. A bicycle oil-can will be found to answer the purpose of an 

 injector very satisfactorily. As the vapour of both carbon bisulphide and carbon 

 tetrachloride is heavier than air, it sinks rapidly to the bottom of the tunnel and 

 kills the insect. The former substance is extremely inflammable and, consequently, 

 the operator should not open the bottle containing this liquid while near a fire or 

 when smoking. xAfter the operation is finished it is advisable to brush away the 

 wood dust from near the base of the trees, for then if no wood dust is found on 

 the next visit it may be concluded that the insect is dead. It may otten be found 

 necessary to repeat the operation a second, or even a third time, as the stem may 

 be attacked by another borer entering it from another branch after the first 

 injection. Neither of the above liquids has any deleterious effect on the trees. 



The treatment adopted in German East Africa for D. usambiea (Morstatt, I.e.) 

 is either to inject the trees with an oil, usually paraffin, or to cut into the vertical 

 tunnel in the stem of the tree a little below the last horizontal tunnel and to spear 

 the insect with wire. The former method is unsatisfactory, for in order to obtain 

 the required result the body of the insect has to be covered more or less with a 

 him of oil and this is not so easy as it may appear. The latter has the dis- 

 advantages that it is a tedious operation, and that it is not advisable, especially 

 in the case of two-year-old trees, to make the deep incision that is necessary. 



Trees attacked by D. princeps if allowed to remain uutreated are either killed 

 outright or broken off by the wind on account of the extensive tunnelling. This 

 insect does not appear to attack trees younger than two years old. 



