168 



Heney (A. K.). Destruction of Mosquito Larvae in Streams : A 

 thorough and economic Method. — Lancet, London, cxcvi, no. 4995> 

 24th May, 1919, pp. 908-909. 



These suggestions are based on work done in 1916 in an Indian 

 cantonment. It is first of all necessary to reduce the slack water of a 

 stream by canalisation, and each part of the water-surface must then 

 be made accessible to the oil. The method by which this is effected 

 in an economical manner is as follows : Planks of lengths roughly 

 corresponding to the varying width of the stream are used. One is 

 put across and fixed at either end in such a way that one of its edges 

 dips vertically 2 or 3 inches into the water so as to form a kind of 

 surface-dam. Another is similarly placed 15 or 20 yards lower down. 

 Kerosene ^^ pint is then poured on to the upper part of the section of 

 the stream between the two planks and is distributed with a sweeping 

 brush over the surface to either bank and made to penetrate the 

 sUghtest indentation at the edges. When the entire section has been 

 covered with kerosene, a third plank is placed in position 20 yards 

 below the second one, which is then lifted, allowing the surface-film 

 of oil with its accumulation of dead and living mosquito larvae and 

 other insects to pass to the next section, where it is again brought into 

 intimate contact with the edges of the banlc by vigorous sweeping. 

 In this way the same oil is used for successive sections. It was found 

 that .1 pint of kerosene oiled 218 Unear feet in the case of a stream 

 6 foot wide, i.e., over 1,300 square feet. The stream was 3,500 feet 

 long, and as only 500 feet had been cleared or canahsed at the time, 

 the 16 pints of oil which gave effective results were used under bad 

 conditions. In a properly cleaned and canalised stream less oil is 

 required and half a mile of such water can be oiled and swept in a 

 morning's work by 3 men. The stream should be divided into lengths 

 of 100 paces by numbers. This enables a record of the work to be 

 kept and topographical data may be collected regarding the incidence 

 of any particular species of larva. Apart from streams, areas of 

 water in which the larvae are confined to the edges in the absence of 

 central weed may be treated very economically by driving the kero- 

 sene along these edges with a brush ; most of the oil can be prevented 

 from escaping to the centre by means of a long board attached to 

 handle, which dips into the water and confines the oil in a kind of 

 temporary channel between it and the bank. 



McDonald (R. E.). The Stable Fly. — Texas Agric. DepL, Mthly. 

 News Bull., Austin, ii, no. 3, 1st August 1919, p. 3. 



The stable-fly [Stontoxys calcitnms] and horn-fly [^Lyijerosia irritans] 

 have very similar life-histories. The measures advocated against them 

 are destruction of the breeding-places, such as manure heaps containing 

 straw or wet stacks, and the use of the foUowing spray : 1 to 2 lb. 

 of soap brought to the boil in 1 U.S. gal. of water ; to this 2 U.S. 

 gals, of kerosene are added and when thoroughly mixed a boiled 

 decoction of 1 lb. of tobacco or tobacco stems. For use this spray 

 should be diluted with 9 parts of water. 



