82 DDT— Killer of Killers 



Aerosols are the most expensive of the DDT formula- 

 tions, but since only a small amount is needed to free a room 

 of insects — a 1 -pound bomb is enough for about 25,000 

 cubic feet of room space — the actual cost for treating the 

 rooms of a house is not excessive. 



It is interesting to note that Dr. Midgley, who unin- 

 tentionally made an important contribution to the field of in- 

 secticides, was himself a viaim of poliomyelitis — a disease he 

 may have contracted through the medium of a fly. 



Long- Lived Action 



Without belittling the ordinary space spray or the aero- 

 sol bomb, we must admit that the one thing about DDT that 

 attracted and held the attention of everyone was the fact that, 

 when properly prepared and applied, a single application of a 

 DDT formulation continues to kill insects for weeks, and 

 even months. This is a unique property not possessed by 

 any other insecticide for household use. Whenever one 

 thought of DDT, he did so in terms of this residual action. 

 As just another ingredient of a space spray, DDT was of little 

 interest, for the sprays that one had been used to buying did 

 a fairly good job. Yet, many of the insect sprays that were 

 first sold to the public during the latter part of 1945 did not 

 have residual action, for the quantity of DDT was too small. 



To be a residual spray, the solution should contain at 

 least 5% DDT. And it should be applied at the rate of 

 about one quart for each 250 sq. ft. of surface, if long-lasting 

 killing is desired with a single application. 



This does not mean that solutions with less than 5 % 

 DDT have no residual action. They do! But remember 

 that you can only spray so much liquid on the wall without 



