68 BULLETIN 416, V. S. DEPARTMENT OF AGEICULTUEE. 



Weeds growing in borders, terraces, etc., and dooryard plants (in 

 the case of fields near dwellings) constitute the sources from which 

 red spiders are able to enter cotton fields. The invasion of fields is 

 accomplished either (1) by travel upon the ground, (2) by travel from 

 leaf to leaf, (3) by the wind, (4) by rain and surface water, or (5) by 

 accidental transportation by farm hands, farm animals, or large 

 insects. 



The control of the red spider is possible either by preventive or by 

 repressive measures. Great expenditures of time, labor, and material, 

 however, are necessary when the latter operation is undertaken. 

 Measures of prevention are far more economical and practical. 



Clean ciilture, or the extermination of weeds and plants which breed 

 the pest, is by far the most vital means of prevention that can be 

 apphed in the case of field and truck crops. 



In cases where cotton is growra within 100 yards of dooryards con- 

 taining violets and other ornamental plants a careful watch of these 

 plants should be maintained in order that they may be sprayed or 

 destroyed. 



By the persistent maintenance of a finely pulverized surface mulch 

 in fields the progress of migrating mites is somewhat retarded and the 

 development of infestation correspondingly discouraged. 



Although the fertilization of cotton land in no way interferes with 

 the status of the red spider, and exerts no direct controlling effect on 

 infestation, yet the judicious use of fertilizers assists the plants to 

 overcome injury. 



Trap crops, rotation, favorable planting time, irrigation, etc., are 

 either of only shght or of negative value. 



Dispersion may be prevented by eliminating the plants in a field 

 which harbor the initial infestation. This may be accomphshed by 

 pulling the first few plants which show infestation, or, in case the pest 

 has secured a good foothold, the elimination wiU be accomplished 

 only by means of plowing up all the affected portion of the field. 

 In either case the stalks should be quickly piled and burned mth the 

 help of a little straw or light trash. 



Spraying for red spiders is effective if it is done with extreme care. 

 There are a few sprays which will give complete mortality when prop- 

 erly applied, but a second spraying is necessary to Mil the individuals 

 that were eggs at the time of the first sprayi'hg. A contact insecticide is 

 absolutely necessaiy, and it is vital that every leaf on an infested plant 

 should be reached by the spray. 



