ENTOMOLOGY

344 SANITARY ENTOMOLOGYwriter knows of no experiments which have been carried out with thecontrol of this species. No doubt care would have to be exercised ittchoosing insecticides to apply to rabbits.Cat lice are comparatively uncommon. A few cases of infestations ofcats with sucking lice have been observed by agents of the Bureau, butthe species concerned has not been determined. The biting louse,Trichodectes subrostratus Nitzsch, seems more common and occasionallycats which have not received proper care are heavily infested.Complete freedom from the biting lice should be secured by a lightbut general application of sodium fluoride 'to the host. Dips containingphenols should be used, guardedly, as cats arc sensitive to theiraction.Dogs are occasionally observed heavily infested with the suckinglouse, Haematopinus piU/erus Burmeister. Tne biting louse, Trichodecteslatus Nitzsch, is far more common than the sucking form and it is especiallyannoying to puppies. This parasite has been found to yield readilyto a single application of sodium fluoride in the dust form. When suckinglice are present two dippings in kerosene emulsion or in one of the standardcoal tar dips should be given at ten-day intervals.THE HOG LOUSEThroughout the entire United States and in fact throughout thegreater portion of the world hogs are infested ~ith a large and repulsiveappearing louse with sucking mouth-parts. The species is known scientificallyas Haematopinus suis Linnaeus. This parasite assumes itsgreatest importance in the wnrmer portions of the country and is especiallyinjurious to hogs which are poorly fed or kept in insanitarycrowded pens.Although the species may live for a few days (about five) apart fromthe host we need consider only the treatment of the host in controllingit. Of course it is well to remove hogs from the pens where they havebeen kept for five or six days after each treatment. The eggs are laidon the hair, especially behind the shoulders, in the flanks along the belly,and behind the ears. They hatch in about thirteen to twenty days, accordingto Watts, the lice mature in about ten to twelve days, and thefirst eggs are deposited a day or two later.Little need be said here regarding the injurious effect of the louse.It is gfmerally 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 beenheld by a number of authors that the species may playa part in the·