228 



FIELD ZOOLOGY. 



erably more than two weeks in different species, though 

 for the majority of our native fleas, the time of develop- 

 ment is about two weeks. 



The eggs of the human flea, Pulex irritans, are laid 

 in the house around the edges of the carpet or in the cracks 



FIG. 94. Egg, pupa, and adult of the cat and dog flea. Pulex serraticeps. 



(Howard.) 



of the floor; here the hatching larvae feed upon such food 

 as offers itself in such places, lint and shreds of clothing, 

 scales of epidermis, and other organic or inorganic dust 

 components. Human beings are also molested by the 

 dog flea. The dog flea is provided with a row of stiff hairs 

 projecting backward from each segment of the abdomen; 

 while the human flea lacks these hairs. The whole 



