. Farm friends and farm foes : a text-book of agricultural science . Agricultural pests; Beneficial insects; Insect pests. INSECTICIDES AND THEIR APPLICATION i6i also ground into a powder which is applied directly to the insects. A tobacco decoction is frequently made by boil- ing the powder or stems in water or by pouring boiling water over them. There is thus formed a concentrated solution which is diluted with cold water until there are about two gallons of decoction for each pound of tobacco used. The decoction may be sprayed upon the in- sects to be killed. Per- haps the way in which toba
. Farm friends and farm foes : a text-book of agricultural science . Agricultural pests; Beneficial insects; Insect pests. INSECTICIDES AND THEIR APPLICATION i6i also ground into a powder which is applied directly to the insects. A tobacco decoction is frequently made by boil- ing the powder or stems in water or by pouring boiling water over them. There is thus formed a concentrated solution which is diluted with cold water until there are about two gallons of decoction for each pound of tobacco used. The decoction may be sprayed upon the in- sects to be killed. Per- haps the way in which tobacco is most commonly used as an insecticide is that of slowly burning the stems in green- houses, producing a smoke which permeates the plants and kills the pests upon them. Vapors and Gases There are certain insects which may most easily be killed by the use of vapors or gases. For this purpose bisulphide of carbon and hydrocyanic acid gas are chiefly employed. The former is a liquid that readily volatilizes on exposure to the air and kills all insects with which it comes in contact. It is used to best advantage against in- sects affecting dry seeds and grains in storehouses, and against insects affecting the roots of plants. Hydrocyanic acid gas is a deadly vapor made by pouring sulphuric acid on cyanide of potassium. It is used to de- stroy white flies in greenhouses and for various enemies of citrus fruits in Florida and California. In the case of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Weed, Clarence Moores, 1864-1947. Boston ; New York : D. C. Heath & Co.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbenefic, bookyear1910
