Parasitism 



389 



is only a tiny fraction of the bulk of the tarantula, but, by the time 

 it is ready for metamorphosis and independent life, it has consumed 

 all the soft tissue of the giant spider ( Petrunkevitch, 1952). 



^-•^5?^^^^^ 



Fig. 10.11. The giant wasp (Pepsis marginata) stinging the tarantula (Cryto- 

 pholis portoricue) preparatory to attaching an egg to its abdomen. (Petrunke- 

 vitch, 1952, Scientific American, drawing by R. Freund. ) 



Plants and animals are susceptible to invasion by several to many 

 species of parasites at the same time, and conversely many parasites 

 can or must have more than one type of host during their lives. The 

 fact that parasites infest other parasites has been immortalized by the 

 jingle: 



Fleas have lesser fleas 

 Upon their backs to bite 'em, 

 And lesser fleas still lesser fleas— 

 And so ad infinitum. 



In a chickadee nest two cowbirds were found both of which were in- 

 fested with hippoboscid flies. Attached to the abdomen of one of 

 the flies were two mallophagan bird lice that thus obtain transporta- 

 tion from one bird to another, and within the bodies of the lice bac- 

 teria were undoubtedly present (Herman, 1937). As many as five 

 links in chains of such hyperparasites and symbionts have been re- 

 ported. 



During the perpetual war between parasites and their hosts many 

 special adaptations have evolved on both sides. The anti-invasion 

 tactics of the host include external anatomical features and internal 



