iQio] California Rodent Fleas 77 



The greatest length of Hfe of a male of any species is seen to be 

 1 7 days ; and the term of life under these conditions for a female 

 was 125 days, somewhat over 4 months. 



In these tests for longevity, it should be borne in mind that 

 no attempt is made to arrive at the initial age of the fleas, but the 

 time is reckoned from the day of removal from the host. 



An effort was made to determine the length of adult life of 

 one species, C. acntus, by feeding the insect newly emerged from , 

 the cocoon. Ten specimens emerging within a few hours of each 

 other were fed on the same day on human blood. One specimen, 

 a female, lived for sixty-four days; at which time the experiment 

 was discontinued. The unfed controls, as well as the specimens 

 given a human blood diet, were kept in ordinary test tubes at 

 room temperature. The activities of these fleas may have been 

 influenced by changes in the temperature and the absence of 

 moisture in the tubes. 



NOTES ON THE FEEDING PROCESS. 



There is a remarkable degree of variation in the feeding habits 

 of the different species of fleas. We have not attempted except 

 in a superficial way, to study the idiocyncracies of the rodent 

 fleas in regard to the biting of their normal hosts. We have, 

 however, quite thoroughly observed the manner of biting under 

 experimental condition with man as a host. Without taking 

 into account the attraction or repulsion which may be exerted 

 towards man as a host, we shall consider the more striking features 

 of the biting of the parasites. We find that the species do not 

 all attack with equal avidity. Pulex irritans the ectoparasite 

 of man, is insatiable in its blood craving. It differs in its relation 

 to man in being more fastidious in its feeding than the rodent 

 fleas. Although its bite is painful, it does not voluntarily feed 

 in one spot for any great length of time. The Pulex irritans dif- 

 fers from all other species (hundreds of specimens of which w^ere 

 tested on human hosts) in that it squirts blood per anum during 

 the act of biting. 



The L. cheopis and C. fasciatus, the normal rat parasites, are 

 found to bite man with equal readiness and will live about the 

 same length of time when fed on human blood. Their biting is 

 well defined and eft'ective, but not nearly so painful as that of 

 Pulex irritans, nor so prolonged as the common squirrel flea, 

 Ceratophyllus acutiis. A specimen of C. acutus when starved for 



