DDT Formulations 89 



dust their plants rather than spray them. Such individuals 

 will find powders specially prepared for them. These pow- 

 ders contain, most commonly, either 3 or 5% DDT, but 

 mixtures of other concentrations can be purchased. These 

 powders can also be obtained with copper or sulfur, or with 

 other fungicides and insecticides; or the farmer or gardener 

 may purchase the straight DDT powder and mix it with his 

 favorite ingredients. 



Save the Surface 



If spraying a solution of DDT on your walls will leave 

 a deposit that will kill insects for months, why not mix DDT 

 with the paint used for the interior of houses and get a finish 

 that will kill insects as long as the paint film lasts? Many 

 imaginative individuals came up with this logical-sounding 

 idea, and many exaggerated claims have been made. Now 

 we can sift fact from fiction. 



The ordinary oil paints and varnishes don't seem to be 

 any too good for mixing with DDT. The DDT mixes with 

 the paint all right, but the dried paint film doesn't have very 

 good killing properties. It seems that the dried oil film traps 

 the DDT and keeps it from coming in contact with the in- 

 seas. That's one way to save DDT — just like covering the 

 ice in the refrigerator with newspapers so it won't melt: You 

 save ice but don't get very good refrigeration. If saving 

 DDT is the object, better keep it in the can instead of lock- 

 ing it up in a paint film. 



Some of the oil-bound water paints and synthetic resin 

 finishes, however, seem to give good results. For some of 

 these products claims have been made that they retain their 

 killing action for over several months. To be effective, the 



