vin] RAT-FLEAS AND BAT-FLEAS 101 



much more readily attracted by the rat than by 

 man. Although the fleas jump on to a man's hand 

 they take some time to begin to feed. They crawl 

 about and seem to have some doubt where best 

 to begin their sucking operations. Also it has been 

 observed that the fleas much more readily fall off 

 a man's arm, when he moves, than they do when 

 a rat moves. It seems that they are able to get a 

 firmer hold on the rat than on a man ; and it is 

 of interest to note in this connection the larger 

 claws of the human flea compared with the claws 

 of the rat-flea. 



It has been shown, in various parts of India, 

 that the number of rat-fleas found on rats varies 

 with the seasons. This seasonal variation of rat- 

 fleas corresponds in a general way with the plague 

 mortality. During the season when plague is bad 

 the average number of fleas per rat is above the 

 mean. During the non-epidemic season it is below the 

 mean. The height of the epidemic corresponds fairly 

 closely with the season of maximum flea prevalence. 



Nineteen species of Pulicidce are more or less 

 habitually obtained by collectors on rats and mice. 

 But the great majority of these may be called casual 

 visitors. Six species of SarcopsyUidce are also oc- 

 casionally found on rats. These are the burrowing 

 chigoes and their allies which usually attack the head 

 and ears of rats. 



