90 DDT — ^Killer of Killers 



binders must permit the DDT to migrate to the surface of 

 the film where the insects can get in touch with it. Since the 

 DDT on the surface will gradually vaporize and be lost, 

 other DDT must take its place if the paint film is to retain 

 its effectiveness. 



One product of this type is sold under the trade name 

 of Pestroy. It is a colorless, synthetic-resin liquid with 6 % 

 DDT. It can be brushed on screens, ceilings, stairs, or other 

 surfaces, and dries in a short time to an almost invisible film 

 which is lethal to inseas but which will withstand consider- 

 able rubbing. The claims for this product are very modest: 

 the manufacturer merely states that one application will re- 

 main eflPeaive for at least three months inside, and at least a 

 month outside. 



