October, '15] ILLIXGWORTH: HABITS OF THE CHICKEN FLEA 



493 



Life-History 



In the study of the development of the fleas every effort was made 

 to duplicate natural conditions. The fact that the adults of this 

 species locate themselves rather permanently greatly simplified the 

 problem of observing their habits of mating, egg-laying etc. 



Newly emerged fleas, of both sexes, were placed in a large glass jar 

 with a young rooster. The next morning ten females and eight males 

 were found located upon the head of the bird. Short, gelatin capsules 

 were then glued to the head, covering individual female fleas, so as to 

 determine the number of eggs produced. During the day from one to 

 two eggs were laid bj' each female, but on the following morning the 

 capsules were full of eggs, and small pellets of blood — -the excrement 

 of the fleas. Careful observations were continued, renewing the cap- 

 sules daily, as long as the fleas lived. It was a noticeable fact that 

 egg-la}4ng took place principally at night— often as many as forty 

 eggs being produced hy a single female at night and only one or two 

 during the day. 



Mating. — A careful, daily chart was kept of the location of the 

 individual fleas on the rooster's head, and it was noted that the males 

 shifted their positions during the night, but remained rather stationary 

 during the day. The females remained practically in one location 

 throughout their life — changing their position only when consid- 

 erably disturbed, in some way. 



Evidently, mating normally takes place at night, for rather constant 

 daily observation failed to discover pairs in copula. On one occasion, 

 some males that had emerged several days previously were placed on 

 the bird, and after a short time they were observed copulating with 

 the females which had been without males for several days. It is 

 rather interesting to note, that in this species the male backs up to 

 the female from below, extending and curving the end of his abdomen 

 backward to secure the union, while he is practically standing on his 

 head. The pairs observed remained attached only about five minutes. 



Longevity Relative to Sex. — Of the fleas under observation on 

 the fowl, the males quickly died off — living from two to six days after 

 feeding and mating — while females lived from eighteen to forty daj^s; 

 producing eggs up to the time of their death. 



In an experiment with fleas kept in jars without food or moisture 

 after emerging, just the opposite was the case, the males greatly 

 outliving the females — some of them remai^ned alive and active for 

 a full month. 



Egg-Laying. — The fleas must evidently feed upon blood before 

 they mate or are able to produce eggs. Several hundred newly 



