PARASITES OF THE DOMESTIC ANIMALS 



cats and may be found upon these animals in common with the species 

 usually infesting them. As a pest of the household the human flea is 

 more commonly found in Europe and the western part of the United 

 States, while in the eastern United States houses may be rendered un- 

 inhabitable for a time by the presence of the dog and cat flea. 



Fleas are of importance as tormenting parasites of man and domestic 

 animals, but of late have received greater attention in the field of med- 

 icine as carriers of disease. It is known that bubonic plague, which 

 during recent years has made its appearance on the Pacific and Gulf 

 coasts of the United States, is transmitted by these insects. Tseniasis 

 of the dog, due to the presence of Dipylidium cani- 

 num, may be conve\^ed to humans as well as to dogs 

 through the intermediation of the dog flea, while a 

 disease of infants known as kala azar, occurring 

 in countries bordering on the Mediterranean, is 

 thought to be transmitted by fleas. 



Usual Hosts. — Our larger domestic animals, such 

 as horses, cattle, and sheep, are rarely attacked b,y 

 fleas. Hogs are somewhat less free from them, but, 

 if occurrmg in these animals, the infestation is most 

 always light and causes little disturbance. Dogs, 

 cats, rabbits, fowls, and pigeons are especial ob- 

 jects of attack. Yomig dogs and those chamed 

 up are more likely to be infested as they live amid 

 conditions favorable to the breedmg of the insects 

 from the laying of the eggs to their full develop- 

 ment, which is particularl}-^ favored by litter and 

 wooden floors. Unlike lice, fleas do not pass their 

 entire cycle upon the host, nor are they limited to a particular species. 

 The dog and cat flea will readily attack man, and in this country is more 

 troublesome to him than the human flea. 



Vitality. — When feeding upon blood, which is the only food taken 

 by the adults, fleas will live from several months to a year. Off a host 

 the dog and cat flea will not survive longer than about two months, the 

 length of life under such conditions being considerably shortened if the 

 w^eather be hot and dr}-. 



Treatment and Control. — Where habitations are infested by these 

 insects it is of first importance as a measure of control that dogs, cats, 

 and other domesticated animals kept about the premises receive treat- 

 ment that will rid them of the parasites. The harbormg animals maj' 

 be dusted with Persian insect powder (pyrethrum), the remedy being 

 applied liberally and driven well under the hair, preferably after the 

 skin has been slightl.y moistened. This will not kill the fleas but will 

 stupify them, in which condition they will drop off or may be combed 



Fig. 37.— Pulex irri- 

 tans, larva. 



