RELATION TO OTHER ANIMALS 



163 



to easily avoid the paw or foot of the animal when it 

 scratches the place where it feels a bite. Although 

 parasitic in so far as it lives during its adult stage upon 

 the host animal, yet the insect moves about freely, 

 and the early stages are passed in most if not all cases 

 among the litter in the nest or den of the host, and not 

 on its body. In its early stages, then, the flea is not a 



Fig. 70 — The jigger flea: a, normal female; b, distended with eggs; c, larva. 



parasite, but rather a scavenger; in its adult stage it 

 feeds on blood and differs from mosquitoes and other 

 flies that have the same habit, chiefly in remaining on 

 the host animal during the period when it is not feed- 

 ing. As soon as an animal is dead and cold the fleas 

 leave it. Of fleas in their relation to man there will be 

 more to say in a later chapter. 



There is one little group of fleas roughly known as 

 "jiggers" that depart somewhat from the normal life 

 history. In these species the female after copulation 

 seeks some host into which it may burrow or imbed 



