332 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



accomplished through preventive efforts rather than repressive, if it 

 is to be economically effected. In the case of certain of our worst 

 crop pests there exists at some stage in their life-cycles a condition or 

 habit which constitutes a vulnerable point of attack. At such times 

 of assailability the agriculturist is enabled to execute control measures 

 both with comparative ease and dispatch. In the case of the red 

 spider, however, no such vulnerable stage occurs. One generation 

 rapidly follows the other with monotonous regularity and homo- 

 geneity. The stages are alike in structure and behavior, the eggs are 

 impervious to the action of sprays, and the feeding habits remain 

 identical from the time of hatching till death. The location of the 

 mites through the winter and spring, their preference for the culti- 

 vated violet and the pokeweed, and the manner of dispersion of the 

 pest, however, lead to the presentation of the following cultural ex- 

 pedients. 



Clean culture.- — First among preventive measures against the red 

 spider is doubtless that of exterminating the weeds and plants which 

 breed the pest. Pokeweed, Jerusalem-oakweed, Jamestown weed, 

 wild blackberry, and all border weeds and underbrush about fields 

 should be burned or grubbed out during the winter or early spring, 

 and should be kept down throughout the summer as far as possible. 

 This plan has been tested in several instances and has given complete 

 immunity the following season. Too much emphasis can not be 

 placed on the importance of destroying, so far as possible, all weed 

 growth — especially the pokeweed, which should be grubbed out by 

 the roots. 



Control on violets. — As before stated, most cases of infestation in 

 urban localities have their origin in borders of cultivated violets grow- 

 ing in nearby house yards. In several instances violets adjoining 

 fields of past severe annual infestation have been thoroughly sprayed, 

 with the result that no red spiders appeared subsequently in these 

 fields. The objection to this treatment is the failure on the part of 

 the average person to persevere with the spraying until the pests 

 have been entirely exterminated. The most satisfactory procedure in 

 such cases consists in the removal and destruction of the offending 

 violets. 



Varietal immunity in cotton. — From several tests conducted in 

 different fields with numerous standard varieties of cotton, and from 

 the information volunteered by farmers from many portions of South 

 Carolina, data have been accumulated which clearly indicate that 

 certain varieties are susceptible to red spider infestation, while others 

 exhibit considerable immunity. Careful observations on a consider- 

 able number of v^arieties grown for the purpose showed that Dixie, 



