355 



below the surface of the soil, and continues, as a narrow tunnel, up 

 the heartwood of the trunk and main branches. Later, a termitarium 

 or nest is frequently constructed at the base of the tree. 



The methods of control and prevention of attack are reviewed. 

 For growing trees, soil fumigation with carbon bisulphide has proved 

 prohibitive in cost and temporary in effect. Lead arsenate in water 

 (I lb. paste to 16 gals.) gave excellent results when poured into a 

 shallow trench round the trunks of .small trees in the early stages of 

 attack; further trials are, however, necessary to determine the effect of 

 repeated treatments on plant life, the minimum strength and number 

 of applications required for effective results, the best time for cariying 

 out the process and, incidentally, the effect upon other insects in the 

 soil. Mercury bichloride is effective but was found to injure the 

 plant ; experiments with weaker solutions should be tried. Poisoned 

 baits have been tested, but the results were not conclusive. A device 

 known as the "white ant exterminator" has been used with success 

 in fumigating certain trees, hollow posts, etc., with arsenic and sulphur. 

 An equally effective and less expensive method is to inject the solution 

 of lead arsenate mentioned above by means of a small syringe into 

 the trunk of a tree, a small hole being bored into the centre of the 

 trunk. After the injection the hole should be closed with a hardwood 

 plug cut off level with the bark, which will eventually overgrow it. 

 Other arsenical mixtures, such as Paris green, would probabl}^ prove 

 as effective ; solutions of sodium arsenite and arsenical cattle dips 

 proved more or less destructive to the plants. 



The relative resistance of various indigenous and imported timbers 

 to termite attack is discussed. As the sapwood is the part most 

 usually infested, it should be removed from the lower parts of posts 

 or piles to at least a few inches above ground level. Serious damage 

 to rafters, joists, flooring boards, fence posts, rails, etc., is almost 

 certain to result unless steps are taken to protect them from attack. 

 Various chemicals, oils and products of coal are recommended, but 

 the expense of treatment is so great that it is seldom practised. House 

 blocks and piles, however, are usually treated in some way. Zinc 

 chloride and corrosive sublimate are thoroughly effective, but are too 

 costly for general use. The former, in a 6 per cent, solution, is especially 

 suitable for the treatment of wood that is to be painted, the latter 

 for dealing with localised attacks. A strong solution of alum in 

 water is also effective, but its use is restricted owing to its solubility 

 and cost. Sodium arsenite is probably the cheapest and most effective 

 poison, and forms the basis of many anti-termite specifics. Wood- 

 preserving oils, creo-tar oil and coal tar appear to protect timber, but 

 repeated applications are necessary if the timber is exposed to the 

 weather, or is liable to split. An efficient mixture for protecting 

 stockyard rails morticed or bolted to termite-infested posts is made 

 by boiling H lb. white arsenic and 21b. commercial washing soda 

 in one gallon of water, and stirring into it, while nearly boiling, 1|- gals, 

 of hot coal tar. Fences require constant attention and free use of 

 poison to protect them from serious injury and ultimate destruction. 

 A small quantity of arsenic, dry or in solution (5-10 per cent.), poured 

 into the top of hollow posts will prevent their destruction ; the 

 protection of solid or split posts is more difficult, but may be effected 

 by pouring a quantity of arsenical solution into a shallow trench around 

 the base of each. This, however, would be costly on large areas, 

 and the risk to stock must be remembered. 



(3393) 2b 2 



