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THE AGRICOLTUEAL NEWS. 



March 19, 1910. 



INSECT NOTES. 



CARBON BISULPHIDE. 

 Part II. 



USE AS AN INSECTICIDE. On account of its peculiar pro- 

 perties, carbon bisulphide has only a limited application in the 

 control of insect pests on plants. It may, however, be used 

 for the destruction of borers in the trunks of trees, by inject- 

 ing small quantities of it into the tunnels of those insects. 

 (Jare should be taken, however, to distinguish tunnels from 

 which the insects have already escaped, since it would merely 

 be a waste of material to apply carbon bisulphide to such 

 holes. Any clean, round hole m a tree infested by borers 

 will probably be found to be the opening through which the 

 adult insect has made its escape. Tunnels in which grubs 

 are still to be found can be distinguished by the quantity of 

 chips and excrement, and sometimes the gummy exudations, 

 which indicate the position of their mouths. The intro- 

 duction of a small quantity of carbon bisulphide into these 

 tunnels will cause the death of the grub within, especially 

 if the opening is immediately closed with wet claj', grafting 

 ■wax or similar material. An ordinary machinist's oiler with 

 a spring bottom will be found very useful for applying carbon 

 bisulphide to borers in trees. 



Another application for the control of insect pests 

 is as follows : Small plants attacked by scale insects, 

 plant lice and similar insects, can be covered over by tight 

 boxe.s in which carbon bisulphide may be evaporated. The 

 most convenient method of use is by means of a small 

 opening at the top of the box or tent used for this purpose, 

 through which the dose of carbon bisulphide is poured on to 

 ab.sorbent cotton or similar material, and the hole then stop- 

 ped with a cork. If a box 10 or 12 inches in diameter be 

 used, a dose of 1 or "2 teaspoonsfuls of carbon bisulphide will 

 be found sufficient. The covers should be left over the 

 plants for three quarters of an hour to an hour, and if 

 the amount of the dose is carefully calculated, the insects 

 ■will be killed without injury to Ihe plants. 



Seeds which are being kept for planting maj* be treated 

 in the same way, using a box, or receptacle, of convenient 

 size, and carefully estimating the amount of material to 

 be used. In the case of clothes moths and other insects 

 which attack stored woollens, furs, feathers, etc., these may 

 be killed by storing these goods in a tight box or chest 

 with an opening in the top similar to the one just described, 

 through ■which carbon bisulphide may be poured, the hole 

 being then closed by means of a cork. This will be found 

 very efficient in protecting from attack all the articles men- 

 tioned, and such a chest or box may even be used for the 

 fumigation of books, papers, food stutfs and all things that 

 are liable to similar attack. 



In using carbon bisulphide in the soil, it should be borne 

 in mind that the direct contact of this material . with the 

 roots of plants is sometimes i7ijuriou.s, but when it is 

 applied in comparativelj' small doses at a little distance 

 from the plant, there is generally no ill effect. It has 

 also been shown that it has no ill effect on the germina- 

 tion of seeds which have been fumigated, when the dose has 

 been approximately twice as great as has already been men- 



tioned. Perfectly pure carbon bisulphide does not stain laces, 

 or any fine fabrics if it comes into contact with them; but the 

 ordinary commercial material is not pure, and care should be 

 taken not to spill it, when delicate clothing is being fumigated. 

 Food stuff's are not injured, and the extreme volatility of the 

 vapour ensures that a short period of thorough ventilation 

 will serve to remove all disagreeable taste and odour. 



In Farmers' Bulletin No. 14.5, of the United States 

 Department of Agriculture, from which the foregoing is 

 largely an extract, it is stated that, as a general rule, crops 

 grown upon soil treated with carbon bisulphide are very good, 

 and a short paragraph is devoted to speculation as to the 

 cause of this favourable condition. Figures are given to show 

 the considerable increase in the products from fields of corn and 

 potatos treated with this substance, and it is mentioned that in 

 a series of experiments with corn, oats, beets, potatos 

 and clover, much the same results were obtained; but 

 the marked increase was in the case of the clover. It was 

 found that the vapour was not detrimental to the bacteria 

 causing nodules upon the roots of this legume, but rather 

 seemed to favour their multiplication. Furthermore, it was 

 found, upon these same plots, that the beneficial influence of 

 the treatment was quite apparent the following year, though 

 less marked than the first year. These observations are of 

 considerable interest in the light of more recent investigations. 

 The etlitorials in two recent numbers of the Ai/riciiltural JS^ews 

 (Vol. IX, Xos. 202 and 203) have been entitled 'The Balance 

 of Life in the Soil', and have contained explanations of the 

 results obtained by partial sterilization of the soil. The 

 ett'ects of soil sterilization have been calculated mostly 

 in connexion with the abundance of soil bacteria, and the 

 relation of the destruction of the beneficial bacteria to that 

 of the injurious forms of protozoan and bacterial life. Carbon 

 bisulphide is mentioned in these as one of the mate- 

 rials experimented with, and the beneficial effect derived from 

 its use is believed to be the result of the partial sterilization 

 produced by its action in the soil. In Antigua, experiments 

 are now being carried out on two plots to determine 

 the effect of carbon bisulphide in the soil, on the growth 

 and yield of sugar-canes, and this substance has been experi- 

 mented with, also, in Porto Pico and in other parts of the world. 

 Nematode worms are abundant in most, if not all, 

 tropical soils, and are very likel^y responsible for more injury 

 to plants than has generally been ascribed to them. The use 

 of carbon bisulphide will probably greatly reduce the numbers 

 of these minute animals, and experiments should show how 

 great the injury from them has been. 



Interesting information as to the employment of carbon 

 bisulphide for the purpose cf controlling the banana weevil 

 borer {Sphenophorus aorclidus) is given in the Report on Agri- 

 culture in Fiji, 1908. At first, attenqits were made to free 

 banana fields from the pest by apjilying tobacco refuse, soot 

 and lime, gas lime, or the refuse from acetylene generators, 

 but the.se were not successful. As is stated in the report, the 

 treatment must be such as will kill the pests that are present 

 in the suckers intended for planting, as well as those that are 

 living in the old, growing ones, and such as will be capable of 

 being employed in keeping the established plants free from the 

 insects. The vapour of carbon bisulphide was observed to be 

 most suitable for the purpose. It was found that the treat- 

 ment of the suckers could be carried out quite easily in 

 barrels, tanks or punts, or even in stacks in a room. In the 

 case of the barrels, tanks or punts, the insecticide was applied 

 in the way that has been indicated already in these articles; 

 in that where the planting material had been piled into 

 stacks, the latter were covered with heavy tarpaulins, and the 

 treatment was then carried out in the usual manner. 



