PLACE OF OILING IN ANTI-MOSQUITO WORK 



167 



stops running, the use of drips is discontinued, and any water left in the 

 stream-bed is oiled with a knapsack sprayer or watering-pot. 



" With the best of care, oil drips will clog, due to suspended solids or 

 heavy constituents in the oil, and must be adjusted as often as necessary. 

 The disadvantage of oil drip-cans is that they will not give satisfactory 

 service without proper attention, may become clogged or be washed 

 away by floods. Their use is generally more effective and economical 

 than the direct application of oil by sprinkler or knapsack sprayer for 

 water in motion." 



Fig. 114- — Utilizing a drip-can for a flowing stream. Note the drip-can fastened 



to the rail to the left of the officer. 



OTHER METHODS OF APPLYING OIL 



Occasionally, the moving water in a ditch or stream may be 

 so little that use of a drip-can is not justified. In such cases, 

 a small bundle of oil-soaked waste, placed at the source of the 

 water will often prove very efficacious. This will give off a thin 

 film for a week or so, after which it may be re-soaked in oil and 

 used again. This same method may be used to control small 

 springs, seepage water outcrops, etc. 



A somewhat similar device, suited for use in similar situations, 

 is a small bag or box of oil-soaked saw-dust. 



Oil-soaked saw-dust has also been used successfully in treating 

 ponds, lakes, swamps, etc., where there is considerable floatage 

 or vegetation. In such cases, it is simply broadcast over the 

 surface, somewhat after the fashion of sowing grain. 



There are many other devices for applying oil to water-surfaces, 

 several of which distribute the oil from above the water; others 



