FLEAS. 11 



small, not being developed for jumping like those of the human flea 

 and other species. 



Nearly all fleas have more or less difficulty in crawling on smooth 

 surfaces or on clothing, yet in time they are capable of making con- 

 siderable progress on clothing, either in a vertical or a horizontal 

 direction. 



The movements of the fleas themselves are of little direct impor- 

 tance in spreading the species. Their jumping powers, however, aid 

 them in finding hosts and securing attachment thereto, and upon the 

 hosts, whether normal or temporary, they may be carried considerable 

 distances. The species are further disseminated by the scattering of 

 eggs as an infested host goes from one place to another and by the 

 dislodgment of the females from the host. Since the fleas leave a 

 dead animal, in this way adults are scattered, and in some instances 

 they may be infected with the disease from which the host died. 

 The greatest spread of fleas is no doubt brought about through the 

 transportation of infested animals from one place to another through 

 the agency of man. In this way rat fleas may be carried between 

 ports in all quarters of the globe on rat-infested ships. Chicken 

 fleas and dog and cat fleas may also be shipped long distances on 

 infested hosts. It is also possible to spread fleas in merchandise, 

 either in the adult or immature stages. Consideration of these points 

 is of much importacce in preventing the spread of plague from one 

 locality to others. 



FLEAS AS CARRIERS OF DISEASE. 



BUBONIC PLAGUE. 



Although the dread disease of man known as bubonic plague has 

 occurred in the United States, the most important outbreak being in 

 San Francisco during the last few years, fortunately it was restricted 

 closely to the portions of the country where it was introduced. 



The earliest records of the disease connect the outbreaks in the 

 human family with death among rats. At the present time the dis- 

 ease is considered to be essentially a disease of rats. Man and other 

 animals become infected through the agency of fleas as a result of 

 these epizootics among rats. 



The malady has a history dating far back in Biblical times. Prob- 

 ably the worst outbreak known began in the eleventh century and 

 culminated in the fourteenth. During this period practically the 

 entire Eastern Hemisphere was swept, and the number of deaths due 

 to the " black death," as it was known in parts of Europe, was appall- 

 ing. Within the last 18 years this malady has caused the death of 

 over 7,000,000 in various parts of the world. During the last decade 

 the disease has broken out in various parts of Africa, Europe, Aus- 

 tralia, Japan, South America, West Indies, and in the United States. 



