THE EED SPIDER ON COTTON. 



Titus, then of this bureau, found severe infestation in fields about 

 Batesbur^, S. C, and the following year he reported severe injury 

 in North Carolina, South Carolina, Georgia, and Alabama. Since 

 then the additional records of Dr. F. H. Chittenden and Messrs. 

 G. P. Weldon, D. T. Fullaway, and others, as well as the writer, 

 have established the presence of this red spider from Maine to Flor- 

 ida and westward to California and in the Hawaiian Islands. With 

 the exception of western Colorado and portions of California no 

 complaints of an alarming nature regarding this pest have come to 



the writer's attention other than from 

 the southeastern portion of the cotton 

 belt. It is here that the red spider ap- 

 pears to have found the conditions most 

 suitable for its development. 



The red spider was described by Har- 

 vey in 1893 as Tetranychus 2-nw.culatus. 

 Harvey considered it quite distinct from 

 the European species T. telar'ms L. His 

 types were from Orono, Me. In 1907 

 Prof. H. A. Morgan published observa- 

 tions on the cotton mite, and apparently 

 accepted the determination of the species 

 as T. telarins. In 1900 Mr. Nathan Banks 

 described the cotton mite under a dis- 

 tinct name — Tetranychus gloveri — but 

 from the study of additional specimens 

 has now concluded that the name is 

 synonymous with Harvey's T. himacu- 

 lahts. Specimens of red spiders on cotton 

 from South Carolina have upon two re- 

 cent occasions been determined by Prof. 

 A. Berlese as the continental species — - 

 Tetranychus telaiuis. As there seems to 

 be considerable doubt on this point, we shall follow Mr. Banks 

 in considering the form with which we are dealing as Tetranychus 

 himacnlatus. 



DESCRIPTION. 



The typical female (fig. 1) is 0.50 mm. long by 0.26 mm. wide, 

 broad-oval, widest in front, and the legs are shorter than the body. 

 Its color is usually brick-red. The t}q:)ical male is 0.27 mm. long by 

 0.15 mm. wide, oval-wedge shape, narrowed behind, the legs about 

 equaling the length of the body, and its color is usually reddish 

 amber. Individuals of both sexes usually possess on either side of 

 the body a dark spot, caused by the food contents. This spot may 

 vary greatl}^ in color, size, and outline. Similarly, depending upon 



Fii;. 1. — The red spider, Tetrany 

 chits l>hnaciilatus: Adult fe 

 male. Greatly enlarged 

 (From Banks.) 



