1 8 Poisonous Arthropods 



color and are distinctly in front of the middle of the thorax, the 

 lateral eyes of each side widely separate. The tarsi of the fourth 

 pair of legs has a number of curved setae in a single series. It has on 

 the ventral side of its abdomen an hour-glass shaped spot. The ftdl- 

 grown female is about half an inch -in length. Its globose abdomen is 

 usually marked with one or more red spots dorsally along the middle 

 line. The male is about half as long but has in addition to the dorsal 

 spots, four pairs of stripes along the sides. Immature females 

 resemble the male in coloring (fig. 9) . 



Regarding the distribution of Latrodectus mactans, Comstock 

 states that: "Although it is essentially a Southern species, it occurs 

 in Indiana, Ohio, Pennsylvania, New Hampshire, and doubtless other 

 of the Northern States." L. geometricus has been reported from 

 California. 



Other Venomous Spiders — While conclusive evidence regarding 

 the venomous nature of spiders is meager and relates almost wholly 

 to that of the genus Latrodectus, the group is a large one and we are 

 not justified in dismissing arbitrarily, all accounts of injury from their 

 bites. Several species Stand out as especially needing more detailed 

 investigation. 



Chiracanthium nutrix is a common European species of the family 

 Clubionidas, concerning which there is much conflicting testimony. 

 Among the reports are two by distinguished scientists whose accounts 

 of personal experiences cannot be ignored. A. Forel allowed a spider 

 of this species to bite him and not only was the pain extreme, but the 

 general symptoms were so severe that he had to be helped to his 

 house. The distinguished arachnologist, Bertkau reports that he, 

 himself, was bitten and that an extreme, burning pain spread almost 

 instantaneously over the aim and into the breast. There were slight 

 chills the same day and throbbing pain at the wound lasted for days. 

 While this particular species is not found in the United States, there 

 are two other representatives of the genus and it is possible that they 

 possess the same properties. We are unaware of any direct experi- 

 mental work on the poison. 



Epeira diadema, of Evirope, belongs to a wholly different group, 

 that of the orb-weavers, but has long been reputed venomous. Kobert 

 was able to prepare from it an extract whose effects were very similar 

 to that prepared from Latrodectus, though feebler in its action. Under 

 ordinary circumstances this spider is unable to pierce the skin of man 



