in] MOUTH-PARTS AND SENSE-ORGANS 51 



In many species the male flea is sufficiently 

 different in outward appearance from the female to 

 be easily distinguished. The male is usually smaller 

 and the last segments of the abdomen are so shaped 

 as to give the look of a tail tilted into the air. The 

 frontispiece represents a male flea and shows this 

 well. The internal organs of reproduction (testes 

 and ovaries) in the male and female are placed near 

 the end of the abdomen. The seminal outlet and 

 common oviduct open to the rear of the sensory 

 plate on the ninth segment of the abdomen. The 

 external genital armature of the male flea is ex- 

 ceedingly complicated and quite unlike that of any 

 other insect. When the sexes are united, the usual 

 position is reversed, and the male is beneath the 

 female. 



It is well known to every entomologist that the 

 hinder segments of insects are often modified for 

 reproductive purposes. In male fleas it is the eighth 

 and ninth abdominal segments which are altered. In 

 the females the eighth, and also often a portion of 

 the seventh, has assumed a peculiar shape. The 

 clasping organs of the male flea are portions of the 

 ninth segment and form together a kind of claw 

 reminding one of the pinchers of a lobster. It is 

 used by the male flea in the breeding season to detain 

 and hold the female. 



Every entomologist also knows that the external 



42 



