122 



THE AGRICCTLTURAL NEWS.''' 



■Apkil 13. 1912. 



INSECT NOTES. 



A NEW METHOD OF CONTROLLING 



TERMITES. 



The following interesting article is reprinted from 

 the Pliilvpfinc Agricultural Rerieiv for December 

 1911, for which it was prepared from notes furnished 

 by D. B. Maekie, Agricultural Inspector:^ 



The various species of white ants, or termites, constitute 

 one of the most serious insect pests on cultivated estates in 

 the tropics. In some countries only dead wood is attacked, 

 while in others, even living plant tissues are devoured, espe- 

 cially in case of the temporary .scarcity of decaying timber; 

 for instance, immediately after the clearing of a forest area. 

 The damage to live plants is usually comparatively insignifi- 

 cant, as compared to the destruction of timber, wooden imple- 

 ments, etc., about estate buildings. Even in places as far 

 north as Washington, D.C., U.S.A., certain species enter 

 houses, and destroy books, furniture, etc. 



Attempts along the line of rendering timber used in the 

 construction of buildings, etc., obnoxious or impermeable to 

 termite attacks have been carried on for the last decade or 

 more, but it is only within the last few years that a really 

 seientific method of directly combating the pest itself has been 

 vorked out. Of course, timbers can be soaked in tar, creasote, 

 or any number of chemical preparations, thus protecting the 

 material from the pest. Moreover, it is a fairly simple, though 

 not always effective plan, to destroy the queens of the species 

 ^vhich construct nests of earth for the rearing of their young; 

 however, since it is almost impossible to destroy an entire 

 colony, even by the use of kerosene, arsenic, or carbon bisul- 

 phide, this method has been rather unsatisfactory. 



It has long been known that termites are particularly 

 .<-ensitive to arsenic and at the .same tinie are very easily killed 

 or driven away either by arsenical baits, or by white arsenic 

 itself deposited in the galleries of the nest. In order to 

 make the destruction of the colony complete, then, it is only 

 neccessary to carry arsenic, in some form, throughout the nest 

 and all the galleries leading to it. It is now known that 

 the vapour of white arsenic and sulphur burned together in 

 a suitable receptacle and introduced into the nest, or even 

 one of the main galleries leading thereto, will permeate the 

 entire structure of the colony leaving a poisonous deposit 

 throughout the course of the fumes, and at the .same time 

 immediately killing nearly all the insects by suffocation. 

 All that is required is a metal box of some sort, which can be 

 readily heated from beneath, connected with a flexible tube 

 which can be inserted into the nest, or main gallery. The lid 

 of the box should, of course, fit tightly, and there must be 

 some sort of a pumping apparatus to force the fumes out of 

 the poison chest through the flexible tube and to the extrem- 

 ity of the smallest gallery, even if it be 20 metres from the 

 central nest. Machines are now on the market at a reason- 

 ble price for performing this operation. The principle is the 

 same in all, that is, a charcoal-burning stove carrying a fume 

 chamber on the top forms one piece, and a hand pump which 

 forces air into the fume chamber — thus driving the fumes into 

 ;ithe nest — forms the second piece. Rubber tubing connects 

 the pump with the main apparatus, and at the end of the hose 

 leading from the fume chest is a metal point for thrusting 

 i|ito the hard structures of the nest. 



About three parts of sulphur to one part of arsenic is 

 the best combination of the fume substances; the heat of the 



charcoal is sufficient to vaporize both the sulphur and arsenic, 

 and these vapours combine more or less, forming arsenic tri- 

 sul[ihide, which is deposited throughout the galleries of the- 

 nest, :iud also upon the individual insects. A nest so treated 

 is probably never again habitable by any colony that might 

 attempt to annex the abandoned structure. 



The operation of this fume apparatus is exceedingly 

 simple, there being but few chances for a mistake to be made 

 in its manipulation. It should be remembered, however, that 

 moist clay, or something similar, should be placed around 

 the nozzle of the fume hose at the point of its entrance into 

 the nest, gallery or infested timber; this airtight packing will 

 prevent the escape of I he fumes. In the case of ground in- 

 fested by termites whose nests are not plainly in evidence, 

 a rod may be used to make an opening into the earth wherein 

 the galleries are suspected to be situated. Except in very 

 heavy soil, these artificial galleries generally break into one 

 or more of the termite tunnels, and thus the fume hose in- 

 serted into the hole made b\- the bar or stick will convey the 

 fumes to the nest and galleries within a reasonable distance 

 therefrom. 



Five minutes of pumping is generally sufficient to im- 

 pregnate the nest and galleries with the fumes. In the case 

 of beams or large timbers in buildings suspected of being 

 infested with termites, a small auger may be used to explore 

 the interior of the wood; when a gallery is located, all that 

 is necessary is to attach the apparatus, pack the point of 

 entrance of the hose nozzle with mud, and pump in the 

 poison. 



A heaping teaspoonful of the poison mixture is usually 

 sufficient for treating an ordinary nest. It should be remem- 

 bered that the insects are not all immediately killed, no 

 matter how thorough the fumigation; but if the operation is 

 well performed, no insect should be in evidence after a period 

 of forty eight hours. This is explained by the fa^t that death 

 is caused not entirely by asphyxiation, but probably by the 

 irritant action of the arsenic as well. 



The foregoing notes appear to be based on experi- 

 ment and trial, and are therefore deserving of considera- 

 tion on the part of those who have to deal with these 

 pests. The question arises, however, as to the effect 

 which arsenic tri-sulphide would exert as an insecticide, 

 since this is an inert and insoluble compound. It 

 would seem that if the sulphur and arsenic were treated 

 in separate compartments, the gases might be mixed in 

 the application with good results, and it may be that 

 the useful effect is due rather to the action of arsenious 

 oxide and sulphur dioxide than to that of arsenic tri- 

 sulphide. 



The application of arsenic in the form of poison 

 bait, or merely placed within the nest or the galleries, 

 is a simple operation which has given good results in 

 some instances. Other methods of control, including 

 the use of cyanide of potassium and the treatment of 

 timbers for building purposes, were mentioned in the 

 Agricultural News, Vol. VII. p, 378. Poison baits for 

 termites may be oaade by mixing arsenic with sawdust, 

 sugar, molasses, sheep manure or horse manure. Any 

 of these mixtures, placed on the ground where the 

 termites are kno,wn to occur, will be eaten and wilt 

 cause the death of many of the insects. Used in this 

 manner, the poison is slowly diffused through the colony, 

 ensuring its destruction in the course of a short time. 



