376 



THE AGRICULTURAL NEWS. 



NOVEMBEE 23, 1912. 



EDITORIAL NOTICES. 



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^gricultiinil gleiufi 



Vol. XI. SATURDAY. NOVEMBER 23, 1912. No. 276. 



l^OTES AND COMMENTS. 



Contents of Present Issue. 



In this number the editorial is concerned with 

 Some Conditions Influencing Soil Nitrification. It 

 ■deals with recent investigations that have been carried 

 out regarding nitrification in soils, and points out the 

 practical application of the results. 



A short article on page .371 gives an account of 

 the behaviour of certain sugar-cane seedlings, from the 

 West Indies and British Guiana, in Queensland. 



A brief description of some interesting plants in 

 Dominica is presented on page 372. These are 

 growing in the Botanic Gardens in that island. 



The present interest in vegetable oils and the 

 sources of their production has led to the inclusion of 

 an article treating of the oil and oil seed trade of 

 Marseilles, on page 373. 



The Insect Notes of this issue contain two articles 

 dealing with methods for protecting coco-nut palms 

 from beetles, and with the curious phenomenon that is 

 shown by what are known as jumping beans. 



Some matters in connexion with the recent inter- 

 national rubber exhibition are brought forward in an 

 article on page 379, and certain suggestions for the 

 -conduct of future exhibitions are made. 



The Fungus Notes appear on page 382. They 

 deal with recently published matter having relation 

 to sugar-cane diseases in Porto Rico. 



Crude Carbolic Acid for Mosquito Larvae. 



It appears from a paper in the Annals of Trop'u'at 

 Medicine and Parasitology for October IS, 1912, thali 

 experiments have been conducted recently in British 

 Guiana, by the Governmt^nt Bacteriologist and the 

 Assistant Government Bacteriologist, in which trial 

 WHS made of the use of crude carbolic acid against! 

 moS(jUiio larvae. 



This substance has been investigated in the 

 special connexiun because conditions are such in 

 Briii.sh (Juiaiia that when ordinary oil is poured oa 

 the ponds and siiiall temporary areas of water it is 

 generally blown to fine side by the strong v. ind, and 

 evaporated before it has a chance of killing the larvae 

 in the water. 



In the case of large amounts of water such as 

 drainage trenches, small fish may be used in the same 

 way as 'millions' for controlling the mosquito pest. 

 Such fish are however useless in the small depressions 

 in land holding temporary water, and it is in these 

 cases tha^. crude carbolic acid has been found to be 

 most cheap and efficient for the purpose. 



In an actual instance, its use was completely 

 successful during the camping out of the Local Forces 

 its employment being combined with the stocking of 

 the larger quantities of water with fish. The carbolic 

 acid, in most of the small pits, killed the larvae ia 

 about one hour; but a much longer time — frequently as 

 much as twenty-four hours — was required to destroy 

 the pupae. 



The authors are inclined to believe that crude 

 carbolic acid applied to temporary small collections of 

 water does not evaporate to any large extent, bu(j 

 remains to impregnate the ground after the water has 

 dried up: and that further there is sufficient of the 

 carbolic acid left even now to render the water 

 subsequently deposited fatal to larvae. 



Laboratory experiments showed that a dilution of 

 1 in 20,000 kills all larvae within two hours, but that; 

 a much longer tiA'ie is required for the death of pupae. 

 For u.se in practice, one teaspoonful to every 2 cubic 

 feet of water, or \ oz. to 16 cubic feet is recommended; 

 'this gives a dilution of about 1 in 10,000, and allows 

 a fair margin of safety to cover errors in calculation.' 



Experience shows that the crude carbolic acid, 

 containing all its impurities, is much more efficient 

 than the purified product. It is thought that this is 

 because its .sticky nature makes it adhere more strongly 

 to the larvae and pupae, and also in some cases it may 

 act by blocking up the syphon tubes through which 

 the insect breathes. 



The possible effect upon animals drinking the 

 treated water is important. In the first place .such 

 water is not attractive to animals because of its tarry 

 smell and blackish colour. In the second the dilution 

 suggested is such that an animal would have to drink 

 a very large quantity of the water before it could ingest 

 a sufficient amount of the carbolic acid to cause 

 poisoning. -- ""^'^ 



A disadvantage of the substance is that it is nob 

 suitable for spraying over large areas such as ground 

 containing a number of small holes, caused it may be 

 by footprints, unless the mixture with water ia 



