MOSQUITO REPELLENTS 303 



antine tested a mixture of these three repellents using six parts of 

 dimethyl phthalate, two parts of National Carbon 612 and two parts 

 of Indalone. This was said to possess synergistic qualities and to pro- 

 tect for a wider range of insects than the individual ingredients. It has 

 been patented by the U. S. Bureau of Entomology and Plant Quaran- 

 tine. It can be said that mosquito repellents designed to keep mosquitoes 

 from alighting and biting have been developed to the point where their 

 usefulness is unquestioned. The aspect of protection by area treat- 

 ment is well developed and has had extensive practical test. 



