2 BULLETIN 416^ U. S. DEPARTMENT OP AGRICULTURE. 



W. B. Parker, H. E. Ewing, and others, as well as the writers, have 

 estabhshed the presence of the red spider from Maine to Florida 

 and westward to Texas, Cahfornia, and the Hawaiian Islands. It 

 is said to be generally distributed in New England, New York, Iowa, 

 Illinois, the southern parts of Wisconsin and Michigan, western 

 Colorado, the Willamette Valley of Oregon, and the interior regions 

 and southern part of Cahfornia. 



ZONAL DISTRIBUTION IN THE SOUTHEAST. 



In the course of our work on distribution it early became evident 

 that the majority of the occurrences in the Southeast were confined 

 to a zone the outer margin of which hes from 60 to 80 miles from the 



Fig. 1.— Distribution of the common red spider. Large dots represent specific occmrences; dotted 

 line incloses the zone of heaviest occurrence in the Southeast. (Original.) 



coast and whose inner margin is from 200 miles (along the Atlantic 

 coast) to 275 miles (along the Gulf coast) inland (fig. 1). In general 

 this zone coincides with the portion of the Piedmont Plateau possess- 

 ing clay or sandy loam soil and excludes the coastal strip of sandy 

 soil. The infested area includes the central belt of oak, hickory, and 

 longleaf pine hills, the sandhills belt, and the granite and meta- 

 morphic gray and red lands. The coastal free area includes the 

 marshes, swamps, and five-oak lands of the coast and the longleaf 

 pine flats and savannas near the coast. Whether this restricted dis- 

 tribution is due to the diversity of plant life or to the differences in 

 cfimatic conditions prevaifing in the respective regions it is diffi- 

 cult to deternnne. Considering the great adaptabifity of the red 

 spider to hosts, it would appear that the matter of the host flora 

 must be one of minor influence. The material difference in humidity, 



