SIPHONAPTERA. 227 



or a human being. The body of the female, congested 

 with the egg burden, bursts in the burrow thus made, 

 and the larvae hatching from the eggs feed upon the 

 blood of the host until the time for pupation. This 

 period is also passed through in the burrow underneath 

 the skin of the victim; and the adults emerge through 

 the festering wound to seek new places where they may 

 make new burrows and rear new jigger flea families. 

 Oftentimes, the irritation incident to the rearing of these 

 jigger flea families is sufficient to cause the death of the 

 host. This flea is not to be confounded with the chigger 

 of our western plains and lawns. The latter animal does 

 not belong to the insects at all, but is one of the mites, has 

 eight legs instead of six, and a differently-segmented body. 

 It ought to be noted here that the female of the hen flea 

 also burrows beneath the skin of the host, and the eggs 

 are laid in the small tumor that forms around the body 

 of the insect. 



The Siphonaptera include also the human flea, the 

 dog and the hen flea, and the fleas infesting so many of our 

 wild mammals, also birds and domestic animals. These 

 fleas are parasitic only during the adult stage, and then 

 mainly at .meal time. 



The eggs of the dog flea are laid between the hairs 

 of the host, from whence they drop to the ground and 

 hatch among the refuse and dust. The larvae seem to 

 feed on organic matter, though they are more adaptable 

 than most other insects, being able to develop on other 

 food, such as dry plant remains, epidermal scales from 

 the body of the host, and possibly excrementitious matter 

 from adult fleas. Some fleas have been reared artificially 

 on dried crumbs or dried blood. The time of develop- 

 ment of fleas ranges from less than two weeks to consid- 



