246 AMERICAN SPIDERS 



In Peru, a similar type of local necrosis is popularly supposed to 

 be caused by the "pododora" (Mastophora gasteracanthoides), a 

 fat, phlegmatic spider with two conical humps on its abdomen. The 

 pododora lives in the vines of grape vineyards and is said to bite 

 the workers when they gather the fruit. Evidence that the pododora 

 is a villain is somewhat circumstantial, and recent opinion inclines 

 to the belief that the real culprit is some other spider, perhaps iden- 

 tical to the arana homicida of Argentina. The symptoms of bites 

 attributed to the pododora are quite similar to those of Lycosa rap- 

 toria, and indicate that the venom largely contains hematoxic ele- 

 ments that destroy cutaneous cells. It is possible that some of the 

 responsibility for the necrosis, which occasionally results in the 

 death of the victim, should be placed on bacterial agents that invade 

 the wound. In any event, the evidence against the pododora is 

 largely discredited by the fact that the venom sacs in the group are 

 tiny, and that the poison itself is known to be impotent in other 

 species. Four species of Mastophora are known from the United 

 States, but there have been no reports of their biting propensities. 

 Indeed, our species are such inscrutable introverts that they exhibit 

 little sign of life even when handled to excess. 



Figuring prominently with the wolf spiders as the cause of spider 

 bites in southern Brazil are various vagrants of the genera Phoneu- 

 tria and Ctenus. Their venom is very active, is exclusively neuro- 

 toxic (as in the black widow), and in experimental animals has been 

 found to cause tetany, convulsions, progressive paralysis, and finally 

 death by suspension of respiration. Its effect on man is far more 

 serious than that of Lycosa or the arana homicida. Satisfactory 

 serums to counteract the venoms of these species are available. 



From such evidence as noted above, it appears that in tropical 

 regions of South America certain lycosids and ctenids are to be 

 regarded as dangerous. In the United States and the temperate 

 regions in general, wolf spiders and their many relatives, despite 

 large size and ferocious appearance, seem to be comparatively 

 harmless. 



The great spiders that Americans know collectively as taran- 

 tulas are capable of inflicting a deep, painful wound with their for- 

 midable chelicerae. Because of their size and hairiness, they are 

 feared, and the usual reports credit them with being extremely 

 dangerous. Dr. William J. Baerg of the University of Arkansas has 

 studied this group of spiders for many years. He has concluded 

 that no species from the United States is able to produce anything 



