302 THE MOSQUITOES OF NEW JERSEY 



in-aid designed to develop a better mosquito repellent. In view of the 

 extensive development of synthetic organic materials, this seemed a 

 good opportunity to attack the problem from the point of view of 

 the relation of chemical structure and physical properties to mosquito 

 repellency. Accordingly, a fellowship was established at Rutgers Uni- 

 versity and has continued up to the present time. 



The first step was to determine the relation of chemical structure to 

 repellency. The second was to study the relation of volatility to prac- 

 tical weather conditions, with special reference to temperature. The 

 third step was to select the molecule of high repellency to mosquitoes, 

 which at the same time is a molecule having the ability to volatilize un- 

 der practical conditions repellent vapors over the longest possible pe- 

 riod of time. The fourth step was concerned with the evaluation of 

 repellent and toxic properties of the selected molecule when applied 

 to the human skin in quantities sufficient to produce mosquito repel- 

 lency. Step one would qualify a large number of compounds, step two 

 would qualify far less, step three would qualify still less, and step four 

 further reduces the number. 



The first successful compound was a mixture of diethylene glycol 

 monobutyl ether acetate, diethylene glycol monoethyl ether, ethyl al- 

 cohol, corn oil, and perfume, later known under the trade name of 

 "Sta-Way Insect Repellent." After a long period this compound was 

 put on the market and immediately met with public favor. Then came 

 the war and the search for mosquito repellents was intensified. The 

 U. S. Bureau of Entomology and Plant Quarantine was charged with 

 the duty of evaluating the worth of mosquito repellents already on the 

 market and any other likely materials on which it could lay its hands. 

 The laboratory at Orlando, Florida, was staffed and charged with the 

 duty of carrying on this work. The fellowship laboratories selected 

 from among their repellency compounds many of the more promising 

 and submitted them to the Orlando laboratory for testing. Out of this 

 testing an unusually powerful repellent, safe for human use, was 

 evolved. The material is ethyl hexanediol, otherwise known as National 

 Carbon 612. In the meantime, two other insect repellents were qualified 

 by the Orlando laboratory. One is known as dimethyl phthalate, a 

 compound which had been patented as an insect repellent. This quality 

 of insect repellency of the phthalates was first uncovered as a result of 

 fellowship work at Rutgers University sponsored by Stance, Incor- 

 porated, from 1926 to 1934. The second is butyl mesityl oxide oxalate, 

 otherwise known as Indalone, developed by the Kilgore Development 

 Corporation. Subsequently the Bureau of Entomology and Plant Quar- 



