Word: ddt
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Dates: during 1940-1949
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Writing in the current Scientific Monthly, Drs. C. H. Hoffmann of the U.S. Department of Agriculture and J P Linuska of the Fish & Wildlife Service deftly spray this "childlike faith in what nature will provide" with mental DDT. Their conclusion is that the real DDT if used with reasonable care, need have no ill effects on desirable wildlife...
...DDT has been whooshed out from airplanes on almost every kind of territory where noxious insects breed. When properly done, say Authors Hoffmann & Linduska, the results have usually been good. As little as one-tenth of a pound of DDT per acre is effective against some mosquitoes. Many serious forest pests, such as gypsy moths, are controlled by somewhat larger doses. Other insects are killed at the same time, but in most cases the insect population of the forest returns to normal a few weeks after the spraying...
Catch Them Vulnerable. Chief reason for this, the authors say, is that not all insects are vulnerable at the same time. Some are tough adults; some are leading sheltered lives under bark or soil. Moderate doses of DDT have little effect on these. If a forest is sprayed when the pest insect is vulnerable, most of the non-pests come through unscathed...
Sometimes insects are benefited by spraying. A woodland plot in Massachusetts, infested with gypsy moth caterpillars, was sprayed with 1.5 lbs. of DDT per acre. With the caterpillars wiped out, the forest remained green and flourishing, and soon had a normal population of non-pest insects. A nearby plot, left unsprayed, was defoliated by the caterpillars and lost two-thirds of its normal insect population...
Insect Irruptions. Hoffmann & Linduska want no one to think that DDT is foolproof. If used incorrectly, they concede that it can cause major trouble Heavy doses (5 lbs. or more per acre) might poison birds and small mammals and cause insect "irruptions." Aphids (plant lice) sometimes multiply disastrously when too much DDT has killed too many of their natural. enemies. But careful observations made all over the U.S. show that moderate spraying with DDT has little or no effect on birds, reptiles or mammals-and successfully gets rid of the pests...