INSECTICIDES AND REPELLENTS 65 



treatments poured onto the hairy parts of the body and distributed 

 with the fingers. 



The DDT and MYL powders issued for the control of body lice 

 are also effective against head and crab lice and are easily applied 

 from the 2-ounce sifter cans. Either powder will usually eradicate 

 an infestation if the hair is not washed within a week after treatment. 

 To be certain of destroying all the nymphs that hatch from eggs, a 

 second treatment after 7 to 10 days is suggested. For a heavy infesta- 

 tion the MYL powder is preferred, as it stops the activity of the lice 

 very quickly. With DDT the lice become abnormally active and 

 cause intense irritation of the skin. The MYL powder may be used if 

 strains of DDT-resistant lice are encountered. 



SCABIES 



Research on scabies treatments was carried out at the Orlando 

 laboratory in Florida and in cooperation with Army Medical and 

 Sanitary Corps officers in other areas. Benzyl benzoate by itself 

 has been used rather extensively for scabies control, but is more 

 effective in the NBIN formula (see p. 64). Benzocaine was included 

 primarily as an ovicide, but it is also a local anesthetic that relieves the 

 itching caused by lice and the scabies mite. 



The NBIN formula has practically no odor, and does not leave an 

 undesirable residue on the body or irritate the skin. For treating a 

 case of scabies, this formula is diluted 1 to 5 with water, as for lice, and 

 applied as a spray or with a sponge. The entire body except the head 

 should be treated, with particular attention to the areas where 

 lesions are apparent. About 60 to 75 ml. of the dilute emulsion is 

 ordinarily required for one treatment. The patient should be in- 

 structed not to bathe for 24 hours. One thorough treatment usually 

 eliminates an infestation, but if a second treatment is required, it 

 should be made about a week later. 



CONTROL OF OTHER MEDICALLY IMPORTANT 

 ARTHROPODS 



BED BUGS 



DDT was found to be highly effective against bed bugs. With its 

 long residual action it seemed to provide the solution of a problem that 

 has long been difficult to handle in army barracks, as well as under 

 many conditions in civilian life. A 5-percent DDT spray applied to 

 the beds (fig. 27) and into cracks and crevices in walls has eradicated 

 these insects from infested buildings. Either a kerosene solution or 

 an emulsion may be applied with a pressure sprayer or power equip 

 ment. The spray should be fairly coarse and wet in order to leave an 

 effective residue. 



In treating a bed it is important to cover completely the mattress, 

 springs, and bedstead, directing the spray particularly to the corners 

 and other places where the bugs hide. This requires about 100 ml. 

 of spray. Cracks in the baseboards and walls, to a height of several 

 feet, should also be treated. Although not all the bugs can be reached 

 with the spray, the DDT residue will kill those that later crawl on the 



