HOUSEHOLD AND CAMP INSECTS 43 



Vermicides. Naphthalene 96 per cent, creosote 2 per cent and 

 iodoform I8 2 per cent appears to be one of the best and speediest 

 killing powders, though it should not be used too freely, as it is 

 apt to cause severe smarting. The preparation should be used 

 on the portions of the garments most likely to be infested, and it 

 not only kills the lice but affords a considerable measure of pro- 

 tection for a period of 5 days. 19 An ointment known as vermijelli 

 is very effective, and when used with the naphthalene-creosote- 

 iodoform powder, the general efficiency is greatly increased. The 

 commercial naphthalene is more active than the pure, its lethal 

 power being dependent in great part on the presence of hydro- 

 carbons and coal tar derivatives. Creosote is a slower insecticide 

 which acts over a longer period, and the iodoform greatly increases 

 the adhesiveness of the mixture for cloth. 20 A mixture of one 

 part each of naphthalene and camphor, with sufficient benzine to 

 render them miscible, and this in turn mixed with 3 parts by 

 weight of sawdust, is recommended as a preventive to be placed 

 in. small, flat sachets measuring i l / 2 by 2^4 inches and worn next 

 to the skin. 21 



Even a handful of finely powdered naphthalene put into the 

 clothes through the opening in the neck and then sleeping with 

 the clothes on the body has been found to result in complete disin- 

 fection if it be done 3 times at 4-day intervals. 22 



A mixture consisting of 300 cubic centimeters each of the oils 

 of lemon grass, pennyroyal and eucalyptus, and powdered naph- 

 thalene 100 drams, put on pieces of cloth or felt, 6-8 drops to each, 

 and fastened to the underclothing at spots where lice generally con- 

 gregate, will prevent breeding. 23 



A mixture of tartaric acid and sodium sulphite slightly moistened 

 with water may be placed in small linen bags and worn underneath 

 the shirt. The temperature of the body produces a reaction which 

 continues for 2 days, giving off a large amount of sulphurous acid 

 which spreads underneath the shirt, kills all the parasites and does 

 not affect the skin. 24 



Precipitated sulphur, an extremely fine amorphous powder, does 



18 The insecticidally inert, but cheaper, magnesium silicate may be sub- 

 stituted for iodoform (Kinloch. Brit. Med. Jour. 2892, p. 792. 1916). 

 1!) Peacock. Brit. Med. Jour. 2892, p. 786. 1916. 



20 Kinloch. Brit. Med. Jour. 2892, p. 789. 1916. 



21 Noel. Rev. Appl. Ent, 4:53. 1916. 



22 Beyer. Military Surgeon, 38:483-91. 1916. 



23 Legroux. Bui. Soc. Path. Paris, 8:470-73. 1915. 



24 Postnicov. Rev. Appl. Ent, 3:122. 1915. 



