344 SANITARY ENTOMOLOGY 



writer knows of no experiments which have been carried out with the 

 control of this species. No doubt care would have to be exercised irt! 

 choosing insecticides to apply to rabbits. 



Cat lice are comparatively uncommon, A few cases of infestations of 

 cats with sucking lice liaA'e been obscrv'cd by agents of the Bureau, but 

 the species concerned has not been determined. The biting louse, 

 Trichodectes suhrostratus Nitzsch, seems more common and occasionally 

 cats which have not received proper care are heavily infested. 



Complete freedom from the biting lice should be secured b}' a light 

 but general application of sodium fluoride to the host. Dips contain- 

 ing phenols should be used guardedly, as cats are sensitive to their 

 action. 



Dogs are occasionally observed heavily infested with the sucking 

 louse, Haematopinus piliferus Burmeister. The biting louse, Trichodectes 

 latus Nitzsch, is far more common than the sucking form and it is espe- 

 cially annoying to puppies. This parasite has been found to yield readily 

 to a single application of sodium fluoride in the dust form. When sucking 

 lice are present two dippings in kerosene emulsion or in one of the stand- 

 ard coal tar dips should be given at ten-day intervals. 



THE HOG LOUSE 



Throughout the entire United States and in fact throughout the 

 greater portion of the world hogs are infested with a large and repulsive 

 appearing louse with sucking mouth-parts. The species is known scien- 

 tifically as Haematopinus suis Linnaeus. Tliis parasite assumes its 

 greatest importance in the warmer portions of the country and is espe- 

 cially injurious to hogs which are poorly fed or kept in insanitary 

 crowded pens. 



Although the species may live for a few daj'^s (about five) apart from 

 the host we need consider only tlie treatment of the host in controlling 

 it. Of course it is well to remove hogs from the pens where they have 

 been kept for five or six days after each treatment. The eggs are laid 

 on the hair, especially behind the shoulders, in the flanks along the belly, 

 and behind the ears. They hatch in about thirteen to twenty days, ac- 

 cording to Watts, the lice mature in about ten to twelve days, and the j 

 first eggs are deposited a day or two later. 



Little need be said here regarding the injurious effect of the louse. 

 It is generally accepted as an important retarding factor in hog raising. 

 Where it is allowed to multiply uncontrolled the skin becomes inflamed, 

 scabby and thickened and the animals present an unthrifty appearance, 

 growth is retarded and fattening is practically impossible. It has been j 

 held by a number of authors that tlic species may play a part in the 



