I9I0] 



California Rodent Fleas 



67 



A similar experiment was conducted at a later date, December 

 5th, 1909, when San Francisco dwellings were still flea infested. 

 The sheets of fly paper were left in the basement of the 

 house for twenty-four hours. The fleas in both experiments 

 were removed by dissolving the "tangle-foot" in alcohol. The 

 parasites which were all identified as Piilex irritans, were dis- 

 tributed on the sheets as follows : 



The table shows that according to our experience, though the 

 data is limited, meat used as a bait under the conditions stated 

 does not exert any special attraction for fleas. 



COPULATION AND EGG LAYING. 



The most prolific of the rodent fleas, Ceratophylliis aciitiis 

 was set aside for studies in mating. The fleas were observed in 

 nature in relation to the host, then microscopically. For the 

 purpose of close observation, a live ground squirrel (Citellus 

 beecheyi) was placed in a mouse jar, where it was kept for a few 

 hours under surveillance. It was noticed that when the animal's 

 body was pressed against the glass that the pelage parted in 

 furrows made by some active objects close to the skin. It was 

 apparent that the squirrel was harboring a large number of active 

 fleas, which occasionally came to view mounted on the hairs of 

 the host. 



The attention of the observer was attracted by a number of 

 fleas which appeared gigantic in size. These proved on close 

 inspection to be paired. Approximately i to every 3 of the total 

 number of fleas infesting the squirrel appeared thus in copulation. 

 The female of the pair covered almost entireh' the body of the 



