76 CIRCULAR 9 7 7. U. S. DEPARTMENT OF AGRICULTURE 



Chiggers were included among the pests against which a clothing 

 treatment was needed. A material was desired that would cause 

 rapid knockdown and also withstand wetting and laundering of the 

 treated clothing. The good mosquito skin repellents, especially 

 dimethyl phthalate and 2-ethyl-l,3-hexanediol, were very effective 

 when applied to clothing but did not withstand water. Since chiggers 

 that crawled onto freshly treated clothing were quickly immobilized, 

 the materials acted as toxicants rather than repellents. Dibutyl 

 phthalate was slightly more resistant to water but was not entirely 

 dependable even after one laundering. Benzyl benzoate was found 

 to give complete protection after two launderings and a high degree 

 of protection after three launderings. A mixture of equal parts of 

 benzyl benzoate and dibutyl phthalate was about as effective as benzyl 

 benzoate alone. Both repellents were adopted during World War II 

 for standard issue (No. 19). 



In subsequent work several compounds were found that were effec- 

 tive after 5 to 10 hot-water launderings. The most promising were 

 diphenyl carbonate, ^-tolyl benzoate, and benzil. They were also 

 effective when incorporated in powders and dusted on the garments. 

 Toxicological studies by the Army Environmental Health Laboratory 

 indicated that the first two compounds cause skin sensitization: so 

 they were not considered safe for use. Although benzil was not ob- 

 jectionable from this standpoint, it did cause skin irritation to some 

 individuals wearing garments impregnated with it in combination 

 with other repellents. 



Of the materials that were considered safe and practicable for use 

 on clothing worn by military personnel, the following gave the best 

 protection against the different pests: 



Mosquitoes: 



2-Butyl-2-ethyl-l,3-propanediol. 



A T -Butyl-4-cyclohexene-l,2-dicarboximide. 



Hendecenoic a.cid (imdecenoic or undecylenic acid). 



Propvl A\.Y-diethv]succinamate. 

 Fleas: 



Hendecenoic acid. 



Benzyl benzoate. 



.V-Bu t vlacetan ilide . 

 Ticks: 



.Y-Butylacetanilide. 



X-Propylacetanilide. 



Hexyl mandelate. 



Indalone. 

 Chiggers : 



Benzyl benzoate. 



Dibutyl phthalate. 



Dimethyl phthalate (and other mosquito repellents). 



Repellent Mixtures for Clothing Treatment 



A great deal of attention has been given to the development of an 

 all-purpose mixture of repellents that would provide in a single treat- 

 ment protection against the most important species of mosquitoes, 

 fleas, ticks, and chiggers. Various combinations of the most effective 

 individual materials were tried, and the one that appeared to give the 

 best all-round results, M-1960, was recommended to the Department 

 of Defense and used during the Korean war. This mixture contains 

 .V-butylacetanilide. benzyl benzoate, and 2-butyl-2-ethyl-l ; 3-pro- 



