ECONOMIC AND MEDICAL IMPORTANCE 249 



These species are all jet-black and more-or-less well-marked 

 with crimson spots. In all of them, the immature specimens are 

 more gaily colored spotted and banded with red or yellow or 

 white. In adult females, the dorsal markings on the abdomen are 

 frequently lost, leaving the whole spider jet-black, though usually 

 it still retains the paler hour-glass marking on the underside of the 

 abdomen. The adult male retains much of the bright color pattern 

 of the immature stages, and never attains the size of the females. 



At this point it is pertinent to note that there is in the United 

 States a second black species, which has been considered only a 

 variety of our common black widow. It is brilliantly spotted with 

 red or yellow marks on the dorsum of the abdomen, and these are 

 retained in the adult female. The pale ventral marking is a trans- 

 verse band or triangular spot, representing at most half of the nor- 

 mal hour-glass markings of many other species. An outstanding 

 characteristic is the fact that the carapace and legs are bright- 

 orange or reddish, whereas in all other known species the former is 

 black, and the legs are black or banded with black and yellow. This 

 "red-legged widow," some years ago named Latrodectus bishopi, 

 occurs in southern Florida in company with true black widows. 

 Its webs are commonly built three or four feet above the ground; 

 they stretch from palmetto to palmetto, resembling some made by 

 the sheet web spinners rather than the more irregular snare of the 

 black widow. Up to the present time there have been no published 

 reports on the poisonous nature of this spider, but there is little 

 reason to doubt that its venom will be found different from that of 

 its close relative. 



A third species of the genus occurs in the United States, but it 

 is less gaudily marked, being ordinarily grayish or light brown. On 

 rare occasions it becomes jet-black, thus assuming the typical color- 

 ation of the group. In some respects this "gray widow," Latrodec- 

 tus geometricus, resembles the common cosmopolitan house spider; 

 it lives in similar situations indoors or outside of buildings. It is dis- 

 tributed around the world in the tropical zone, and is the dominant 

 species over most of Brazil and in the eastern coastal portions of 

 South America. Although it is venomous, its reputation is far in- 

 ferior to that of the black widow. In the United States it is found 

 in southern Florida, especially in the Miami region but also along 

 the west coast, and it has been reported from several points on the 

 coast of southern California and Mexico. 



The black widows themselves are tangled web weavers that spin 



