OCR Text |
Show I Spraying in Summer Will Not Halt Grubs Destroying Eggs Fails To Step Winter Atte;k Spraying cattle in summer with benzene hexachloride, rotenone or other insecticides, new or old, does not prevent grub infestation in winter. win-ter. Although there is nothing new in that statement, the need for repeating repeat-ing it is plainly indicated by an account of spraying dairy cattle in one of the corn belt states. The work was given considerable publicity, pub-licity, with erroneous conclusions. In til i s case, older animals of the herd were sprayed with DDT. Heif-I Heif-I ers and calves were not sprayed ! because they were running in pas- Dipping method is favored by some cattlemen to control grubs and other infestations. ture. Spraying them would have required getting them up and handling han-dling them. The following winter, it was noticeable that the cows which had been sprayed were not infected with grubs. The young stuff was I peppered with them. The natural conclusion was that a summer spray of DDT was effective. That conclusion is unwarranted because, as entomologists know, older cattle seldom if ever have grubs of the heel fly. The young animals are the ones that suffer. The department of agriculture says: "Many substances have been applied to cattle to keep away heel flys and to kill the eggs depositee! on the legs of the animals. All have been found to be either ineffective or impractical. The best time for attacking the pest is when the grubs are in the backs of cattle." |