THE RED SPIDERS ON COTTON AND HOW TO 

 CONTROL IT. 



General appearance and nature of damage . . 3 



Distribution in the Southeast 5 



Extent of injury 5 



Description of the red spider 6 



Seasor.r.l history and habits 7 



Relation of weather to breeding 8 



Page. 



Dispersion 9 



riants attacked 10 



Natural enemies 10 



Remedies for the red spider 10 



Summary of remedies 15 



BY THE adoption of the preventive measures described in this bul- 

 letin it is possible to avoid the losses caused by the so-called red 

 spider (fig. 1), a minute creature which causes serious injury to cot- 

 ton in the Southern States. Injury by the red spider in cotton fields 

 may occur from the middle of June until the middle of September. 

 It consists in a rusting and drooping of the leaves and sometimes in 

 the death of the affected plants over considerable portions of the 

 fields. For many years tliis trouble has been called "rust" by cotton 

 planters, who concluded from the reddening of the leaves that it 

 was a disease. The injury, however, is caused by the presence on the 

 cotton leaves of midtitudes of small mites called "red spiders." 



GENERAL APPEARANCE AND NATURE OF DAMAGE. 



The presence of the pest is first revealed by the appearance on the 

 upper surface of the leaf of a blood-red spot. As leaves become more 

 infested they redden or turn rusty yellow over the entire surface, 

 become folded, then tuni brown and dry, and finally drop. The lower 

 leaves usually are fii"&t attacked, but infestion spreads upward until 

 often only the bare stalk and one or two termhial leaves remain. 

 (See figs. 3, 4, and 5.) Such plants almost always die. 



In severe cases the dropping of the leaves is sufficient to ]>revent 

 the development of hnt. The loss of foliage, however, is always 

 accompanied by the shedding of bolls, which may amount to the total 

 loss of fruit or merely of the younger bolls. On the plants other 

 than cotton, which the red spider often attacks, the appearance of 



' Tetranychus tclarius L., generally known as T. himaculatus Harvey, and in some publications as 

 T.glovcri Bks.; order Acarina, family Tetranychidae. 

 Note.— This bulletin is a revision of Farmers' Bulletin 735. 



96617°— 17 3 



