2 THE EED SPIDER ON COTTON. 



from South Carolina and Georgia. In 1904 Mi\ E. S. G. Titus,' 

 then of this bureau, found severe infestation in fields about Bates- 

 burg, 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 establish the presence 

 of the common red spider in Maine, Massachusetts, New York, New 

 Jei-sey, District of Columbia, Virginia, North Carolina, South Caro- 

 lina, Georgia, Florida, Alabama, INIississippi. Louisiana, Texas, Ohio, 

 western Colorado, Wyoming, Idaho, Washington, California, and 

 the Hawaiian Islands. 



The red spider was described by Harvey ^ in 1893 as Tetranychus 

 2-maculatus. Harvey considered it quite distinct from the European 

 species T. telarius L. His types were from Orono, Me. In 1907 Prof. 

 H. A. Morgan published observations on the cotton mite, and ap- 

 parently accepted the determination of the species as T. telarius. 

 In 1900 Mr. Nathan Banks described the cotton mite under a dis- 

 tinct name — Tetranychns gJoreri—hut from the study of additional 

 specimens has now concluded that the name is synonymous with 

 Harvey's T. himaculatus. Specimens of red spiders on cotton from 

 South Carolina have upon two recent occasions been determined by 

 Prof. A. Berlese as the continental species — Tetranychus telariKs. 

 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 

 Tetranyclms himaculatus. 



DESCRIPTION. 



The typical female (fig. 1) is 0.46 mm. long by 0.24 mm. wide, 

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

 Its color is usually brick-red. The typical 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 greatly in color, size, and outline. Similarly, depending upon 

 the host plant and upon locality, the general color of the red spider 

 is subject to great variation. 



The eggs are very minute, but in proportion to the mites they are 

 large. They are perfectly round, and when first laid are as clear as 

 water. Each female lays (in the months of June, July, and August) 

 about 50 to 60 eggs, depositing about 6 per day for a period of about 

 nine days. Less than 3 eggs or more than 9 are rarely deposited each 



1 Cir. 65, Bur. Ent., U. S. Dept. Agr., 1905. 



2Cir. 104, Bur. Ent., U. S. Dept. Agr., 1905. 



3 Ann. Rept. Maine Agr. Exp. Sta. for 1892, Pt. IV, pp. 133-146. 



