Manual on DDT Insecticide

DDT was first synthesized by a Germ an chemist in 1874, but its insecticidal properties were not discovered until 1939, when a Swiss chemical firm (J. R. Geigy, Inc.) began to use it in the control of moths and plant lice. The U. S. Department of Agriculture tested a sample in November 1942, and found it to be effective against nearly all insects. During 1943 and the first six months of 1944, that Department conducted extensive experiments to determine how DDT could best be used against the insects which threaten the health, morale and military efficiency of our troops. During this period DDT was available only in quantities for experimentation. The large scale manufacture of this substance has been achieved during time of war only through the high priorities accorded it by the War Production Board, the Army and the Navy. In 1943, when the Department of Agriculture laboratory at Orlando, Fla., was sending its first reports on DDT to the Army and the Navy, many of the accounts were difficult to believe. There was a report of a duck swimming in a pond which had been treated with DDT for larvicidal action. The duck waddled over to a large puddle and resumed his swimming. All the larvae in the second puddle were later found to be killed. A cage full of experimental flies were unintentionally killed when DDT dust was mixed at a great distance from the cage. Laboratory technicians having traces of DDT on their hands have ruined experiments when they picked up small cages in which experimental insects were kept; all the insects were killed. It was reported that one (1) part DDT in 20,000,000 parts of water killed 100 percent of larvae; one (1) part DDT in 100,000,000 parts of water killed 40.7 percent of larvae. As reports continued to come in, it was realized that DDT could accomplish all the feats ascribed to it, and many more. The prolonged residual effectiveness of DDT against insects constitutes its main advantage over previously used insecticides.