FLEAS AND THEIR CONTROL. 9 



hosts, as well as occasionally on man and other animals. AVhile they 

 cause these hosts much annoyance and, as has been pointed out, are 

 also responsible for the infestation of dogs by tapeworms, serious 

 injury seems to be rare. In the case of valuable dogs and cats, how- 

 ever, it is often desirable to rid them of fleas, and in all cases where 

 these animals are closely associated with man the control of the fleas 

 upon them is of importance. As will be seen by comparing figure 1 

 with figure 5 the dog flea is quite different from the sticktight flea 

 in structure as well as in size. The adults do not remain attached to 

 the host in one place, but the life history is not vastly different from 

 that of the sticktight flea. Breeding takes place in similar materials 

 in situations occupied by the host animals. Mr. Theodore Pergande, 

 working with the dog flea at Washington, D. C, found the life cycle 

 from egg to adult to be completed within 17 to 37 days. It is thus 

 seen that a great number of fleas might be produced in and beneath 

 an unoccupied house in a comparatively short period. 



Both of these species have a very wide distribution, being found 

 in practically all parts of the world where dogs and cats are found. 



THE RELATION OF FLEAS TO BUBONIC PLAGUE. 



During recent years bubonic plague has been introduced into the 

 United States on both the Pacific and Gulf Coasts. The infestation 

 in California has persisted for a number of years, although closely 

 held in check through the efforts of the Public Health Service and 

 the State board of health. The disease around San Francisco not 

 only persisted among the rats, but gained a foothold among ground 

 squirrels in the counties adjacent to San Francisco Bay. 



During the year 1914 the disease broke out in New Orleans, but 

 strict quarantine measures and an energetic campaign against the 

 rats ^ kept the malady from spreading and limited the number of 

 human cases. 



With the reduction in numbers of rats and mice there is a cor- 

 respondingly great decrease in the numbers of the species of fleas 

 which infest them and which may play a part in carrying bubonic 

 plague. The cleaning up of the breeding places of rats and the de- 

 struction of their nests will accomplish the extermination of a large 

 number of fleas in the immature stages. 



Persons resident in districts where plague occurs among the ground 

 squirrels should remember that there is danger of infection from the 

 bites of fleas which infest these animals. 



1 The methods of rat control :iie discussed in Farmers' Bulletin 896, U. S. Department 

 of Agriculture, by Mr. D. E. Lantz, of the Bureau of Biological Survey. 



