. Cyclopedia of farm crops. Farm produce; Agriculture. 44 MEANS OF CONTROLLING INSECTS came into use Paris green poison, which was des- tined to revolutionize insecticidal methods. In 1872, it was suggested that a Paris green spray be applied on cotton plants for the cotton worm and on apple trees to kill canker-worms. Six years later it was found that the poison spray effectively checked the codling-moth, and this gave a new impetus to the warfare against insects, which has finally resulted in the modern formidable array of insecticide materials and elaborate machinery for their application.
. Cyclopedia of farm crops. Farm produce; Agriculture. 44 MEANS OF CONTROLLING INSECTS came into use Paris green poison, which was des- tined to revolutionize insecticidal methods. In 1872, it was suggested that a Paris green spray be applied on cotton plants for the cotton worm and on apple trees to kill canker-worms. Six years later it was found that the poison spray effectively checked the codling-moth, and this gave a new impetus to the warfare against insects, which has finally resulted in the modern formidable array of insecticide materials and elaborate machinery for their application. The materials used as insecticides may be divided into thi'ee groups, based largely on the two differ- ent ways in which insects eat. Some insects, as caterpillars, potato-beetles, and many others, have their mouth-parts provided with strong jaws which enable them to bite oft' and swallow solid particles of their food-plants. (Figs. 53, ) Many other insects, of which the plant-lice, stink-bugs, scale- insects and mosquitos are familiar examples, have their mouth-parts drawn out into fine threads which are forced into the plant-tissues along a stiff, sup- porting beak ; such sucking insects are unable to eat solid particles and hence cannot be fed a poison sprayed on the surface, for they can suck only liquid food from the inner tissues of the plant-host. (Figs. 54, 66.) To kill biting or chewing insects, it is necessary only to apply a poison on the surface of the plant where they are going to feed. But each individual sucking insect and not a certain part of the plant must be hit with some material that will soak into its body and kill, or that may smother by covering the breathing holes along the sides of the body. The third method is fumigation. Biting insects.âThe insecticides used for killing biting insects consist mostly of poisons which have for their basis white arsenic. This substance can not be used alone, as it dissolves slowly, and this causes it to burn foliag
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