THE LIFE HISTORY AND CONTROL OF FLEAS 363 



58 days, the Indian rat flea 38 days, and the bird or chicken flea (Cera- 

 tophillus galUnae) 127 days. When fed daily this longevity was greatly 

 increased; human flea 513 da^'s, European rat flea 106 days, dog flea 

 234 days, Indian rat flea 100 days, and the bird flea 345 days. Mitzmain 

 found the European rat flea to live 160 days in California and the ground 

 squirrel flea (Ceratophyllus acutus) 64 days. In warm weather the 

 longevity without food is but a few days. 



The human flea (Pulex irritans) (figs. 66, 67) was formerly thought 

 to restrict its attention largely to man. Investigators have found, how- 

 ever, that it probably develops normally on the hedgehog and others 

 state that it is occasionally found on dogs and cats, especially during the 

 winter. Our own observations indicate that it is a very common parasite 

 of hogs ; so much so in fact that it might be called the hog flea instead 



Fig. 67. — The human flea, PuUx irritans: Adult male. Greatly enlarged. (Bishopp.) 

 From U. S. D. A. Bull. 248, figs. 5, 6. 



of the human flea. Also that it may be found in considerable numbers 

 on dogs at all times of the year even in regions where it is not a pest 

 of importance to man. It has been taken on several species of rats, but 

 in limited numbers. This form appears to be well adapted to a free 

 existence, usually leaving the host after partaking of a blood meal and 

 this habit may tend to make it of greater importance as a disseminator 

 of disease. It has almost world-wide distribution but its abundance in 

 diff^erent regions varies greatly. In the United States it is very prev- 

 alent in California and the Southwestern States where it is the principal 

 cause of flea annoyance to man. 



The dog and cat fleas (Ctenocephalus canis Curtis and Ct. felis 

 Bouche (fig. 65) may be discussed together as their habits appear to be 

 very similar and as some authors still believe they are not distinct species 

 but only varieties. They have a rather wide range of hosts, including the 

 dog, cat, man, and a number of wild animals, especially of the dog and 



