18 



CIRCULAR 15. FISH AND WILDLIFE SERVICE 



scrub and sapling growth with 5 

 pounds of DDT to an acre caused a 

 heavy bird mortahty. Three of 

 the commonest species were re- 

 duced 80 percent in numbers, and 

 the total reduction for the 5 com- 

 monest species was 65 percent. 



The aerial application of DDT 

 in oil at a rate of 1 pound to an 

 acre to a 1-mile section of Back 

 Creek, W. Va., caused a nominal 

 kill of fishes but a heavy kill of 

 bottom fauna. At the lower end 

 of the 1-mile section more than 

 90 percent of the aquatic organ- 

 isms were killed. 



Laboratory tests of several new 

 insecticides showed that chlo- 

 rinated camphene was consider- 

 ably more toxic to fishes than was 

 DDT; TEPP (tetraethyl-pyro- 

 phosphate), parathion, and bis 

 (p-chlorophenoxy) methane were 

 about of the same toxicity as DDT; 

 and chlordan and benzene hexa- 

 chloride were slightly less toxic in 



field formulations. In chronic tox- 

 icity tests with quail, DDT ap- 

 peared to be slightly more toxic 

 than were DDD, benzene hexa- 

 chloride, and chlorinated cam- 

 phene. The last named was ap- 

 parently the least toxic of the 

 group. 



Detailed studies of the effects 

 of DDT on oysters indicated that 

 these shellfish are fairly resistant. 

 Spraying of oyster beds at the 

 rate of li^ pounds of DDT to an 

 acre, applied either as an emulsion 

 or in an oil solution, caused no 

 mortality among adults or young. 

 Application rates up to 5 pounds 

 to an acre showed no evidence 

 that spraying shell piles for fly 

 control appreciably reduced the 

 value of the shells for collecting 

 set. In fact, spraying the shells 

 with DDT appeared to have a posi- 

 tive value in that it prevented the 

 attachment of barnacles. 



RECOMMENDATIONS FOR MINIMIZING 

 DANGER TO WILDLIFE 



Additional investigations have 

 shown no cause for modifying ap- 

 preciably the recommendations 

 given first in Fish and Wildlife 

 Circular 11, DDT: Its Effect on 

 Fish and Wildlife, and restated in 

 the summary of the 1946 studies. 

 With minor revisions these are 

 given again herein : 



Use DDT for the control of an 

 ineect pest only after weighing 

 the value of such control against 

 the harm that will be done to 



beneficial forms of life. Wher- 

 ever more than a small area is in- 

 volved, consult county agricultural 

 agents. State or Federal ento- 

 mologists, wildlife and fishery bi- 

 ologists, and United States Public 

 Health Service officials. 



Use DDT only where it is 

 needed, and in all cases use only 

 the minimum quantity necessary 

 for control. Wherever it is ap- 

 plied by airplane, provide careful 

 plane-to-ground control to insure 



