76 Annals Entomological Society of America [Vol. III. 



A Loemopsylla cheopis was fed for 35 days, escaping on the 

 36th day. One C. acntiis died after 58 days and another one at 

 the end of 5 1 days. The common brown rat fiea C. fasciatiis, 

 proved to be the most persistent feeder of them all. Unfortunate- 

 ly one of them was permitted to escape after feeding on its 

 induced host for 63 days. Another of the group suQered no ill 

 effects from its enforced diet for 98 days; and the sole survivor 

 had been nourished by its foster host since its removal from the 

 rodent host for a period of five months. The experiment was 

 discontinued, but the ])arasite survived a week longer in a 

 starved condition. 



LONGEVITY RELATIVE TO SEX. 



We have noted the relati\e longevity of the sexes under the 

 conditions of experiments in which fleas were fed on human 

 blood alone. 



We shall take for consideration the two species common to 

 rats, L. cheopis and C. fasciatns and the predominant squirrel flea, 

 C. acutus. Four tests with ('. fasciatns gave the following data: 



C. fasciatns. 



Six males of this species averaged 8^^ clays, the maximum life 

 being 17 days. Fifteen females gave an average of 2^2 4-5 days 

 with a maximum of 125 days. The two unfed controls (male) 

 of this series lived for 3 days, and the two control females lived 

 for 5 days. 



L. cheopis. 



Two tests with a total of seven males of this species gave 

 an average of 10 j -7 days and a maximum period of 15 days. 



Three females lived 28 1-3 days as an average and a maximum 

 period of 49 days. 



The two unfed male controls li\'ed 5 days and in foiu- females 

 the average was ^\ days and the maximum 7 days. 



C. acntns. 



One test with this species furnishes the following data : Three 

 males averaged 1 1 days, and gave a maximum of 11 days. 



Five females averaged 15 1-5 days. 'I'hc longest life was 53 

 (lays. 



The unfed males averaged 3 days and showed a maximum of 

 4 days. The female control lived 5 days. 



