August, '14] MCGREGOR: RED SPIDER CONTROL 327 



The distribution of the red spider is very general. It has been 

 reported from Maine to Florida, and from South Carolina to Oregon, 

 and it doubtless occurs in every state of the Union. What the original 

 host plant of the common red spider was, seems impossible now to 

 determine. The pest is a very omnivorous creature, having been 

 recorded at Batesburg from 130 hosts. It is most abundant ordinarily 

 upon the Enghsh violet, sweet pea, hollyhock, morning-glory, bean, 

 dahlia, tomato and Jerusalem-oakweed. The commonly cultivated 

 English violet seems to serve as the winter host for the vast majority 

 of mites in urban localities. The same mite species has been found 

 also on species of wild violet well removed from domestic habitations. 

 The ubiquitous pokeweed serves as an early seasonal host, but is 

 probably chiefly in the nature of a secondary host rather than that 

 of a normal winter food plant. 



The usual time of the first conspicuous appearance of the red spider 

 in cotton fields is about June 30. The pest establishes itself some time 

 previous to this, however, and it is seldom difficult to find migrated 

 females on nascent seedlings in exposed situations. Practically all 

 occurrences in urban localities have been intimately associated with 

 cultivated violet plants and doubtless originated from them. On the 

 other hand, with very few exceptions rural cases of infestation are 

 traceable to pokeweed stalks growing at the field borders or on the 

 terraces. 



The description of a particular rural occurrence will serve to illus- 

 trate a typical case of origin from pokeweed. In this instance the 

 infestation was seen to grow increasingly severe as one approached a 

 certain point on a terrace. Converging from all directions toward 

 this center, infestation clearly became heavier until an area was reached 

 where the plants were denuded of foliage. Precisely in the center of 

 this area there grew a large pokeweed stalk. It was "alive" with 

 mites and was lightly festooned with their webbing. 



It is not yet entirely established whether or not the poke plant 

 functions as a true winter host. The plant is a perennial, and the 

 stalks die to the ground in the late fall. At the base of the dead stalks 

 are to be found the soft, fleshy roots which are very succulent. In 

 addition, at the crown of the roots, at about the ground level, there 

 are always to be found through the winter months the tender dormant 

 buds which give rise to the stalks of the following spring. Upon 

 November 23, following several severe frosts at Batesburg, S. C, a few 

 mites were seen apparently feeding on these winter buds. 



In South Carolina there are usually about sixteen^ generations of 

 red spiders each season. In 1911 there were seventeen, in 1912 there 

 were sixteen and in 1913 there were again sixteen successive broods 



