Fleas 



infesting cats and dogs, both domestic and wild, upon the 

 Egyptian Ichneumon and the common European pole-cat, the 

 striped hyaena, the common hare, the raccoon, and it also bites 

 human beings. The food of flea larvae has been the subject of 

 some discussion. The old statement that the female flea disgorges 

 drops of blood upon which her young feed, seems true only to a 

 small degree. Laboulbene, the famous French entomologist, at 

 first believed that blood was necessary for the nourishment of the 

 larvae, the reddish colored contents of the digestive tract making 

 him think so, but he found that they would flourish and com- 

 plete their metamorphoses 

 in sweepings in which 

 there was no trace of blood. 

 He concluded that all that 

 has been said about P. 

 irritans (the human flea 

 of Europe) nourishing its 

 young on dried blood is 

 very problematic. Mr. W. 

 J. Simmons found flea lar- 

 vae feeding upon a dust 

 composed of fragments of 

 cuticle, hairs, fibers, and 

 pellets of dried blood, 

 the last being probably 

 the natural excreta of the fleas. The writer has fed them suc- 

 cessfully upon moist bread crumbs, and it is reasonably certain 

 that they will feed upon the dust or minute particles of almost 

 any kind of organic matter. 



The minute, delicate, whitish eggs hatch into slender, worm- 

 like larvae, which, when full-grown, spin delicate cocoons, and 

 transform to pupae, from which issue the adults. Rather more 

 than 100 species are known, of which about 30 have been found 

 in the United States. 



In the recent important and alarming indictments of certain 

 species of insects as carriers and transmitters of certain human 

 diseases, fleas have not escaped. Grassi considers that the cat 

 and dog flea (P. serraticeps) is an intermediate host of Taenia 

 (tape- worms), while Simon and others have brought forward 

 some proof that certain fleas convey the germs of the bubonic 



192 



Fig. 113. Sarcopsylla gallinacea. 

 (From Insect Life) 



