A control program using 0,5 percent geiinmexane powder (D,03/V) 

 vas undertaken in houses in humid Kenya hills (Teesdale 1952). 

 Reapplications had to be made every month or two to control nymphs 

 that had hatched from eggs, the latter being resistant to the 

 chemical. Killing effects diminished in treated huts fifty days 

 after application. The low cost of gamraexane was said to allow 

 its purchase and tise by Africans. 



Although most recent workers favor BIC dusts over spray so- 

 lutions, Anderson (l%7j reported good control in Somaliland coffee 

 houses with a three percent solution of gammexane in diesoline, 

 "666 spray* (crude benzene hexachloride , 12$, gamma isomer) at a 

 dosage of 1,250 mgm. per square foot of soil was recommended by 

 Hocking (19^-6 J, who found DDT at the same dosage less effective. 

 On the basis of experiments in two localities in Kenya, Heisch 

 and Furlong {195U) recommend a spray of gammexane wettable powder 

 P. 520 rather than gammexane insect powder for tampan control. 



Investigators have reported that DDT is of less effective- 

 ness than gammexajie in controlling tampans. Among these, Jepson 

 (1947) found that five percent DDT dust is slower and less ef- 

 fective than gammexane, although after about three weeks a mor- 

 tality of fifty percent to eighty percent obtained. Holmes (1953) 

 also indicated that gammexane provides a more complete and rapid 

 kill than DDT. Annecke and Quin (1952) considered that various 

 types of DDT applications lacked siifficient residiial effect to 

 be considered useful. 



The inefficacy of many chemicals for killing 0. raoubata and 

 the usefulness of gammexane and of E605F (diethyl-punitrophenyL- 

 nono-thio- phosphate) for this purpose were reported by Enigk (19^8). 

 Belgian tests with three preparations of the gamma isomer have 

 been reported by Pierquin (1950). Sprays of '"Cyclotox"' contain- 

 ing a large proportion of the gamma isomer killed about half the 

 ticks in eight to ten days when applied in Belgian Congo huts. 

 In the laboratory, where the ticks could be kept in closer contact 

 with the chemical, all died after varying lengths of time with 

 different concentrations eind preparations (Himpe and Pierquin 

 1951). The authors conclude that spraying a volatile substance 

 on soil is of less value than mixing it with soil. 



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