66 BULLETIN 416, U. S. DEPAETMENT OF AGEICULTUEE. 



were hit by the preparation were killed. Since the making of this 

 spray requires less time and care than is the case with flour paste, 

 and since its efiicacy appears to be just as good, it would appear 

 thatthis simple mixture should be given further consideration. 



Resin Wash. 



An insecticide containmg, resin 2 pounds, caustic soda one-half 

 pound, fish oil one-fourth pint, and water 10 gallons was given a 

 thorough test on hejtivily infested beans and cotton. In both cases 

 all red spiders were killed. This preparation possesses the valuable 

 quaUty of spreading, and is an excellent red-spider spray. The only 

 objection to its general use is the fact that it is not quickly or easily 



prepared. 



Soap Solutions. 



A common brand of fish-oil soap, at the rate of one-fourth pound 

 to 2 gallons of water, was applied to mites on beans and cotton. The 

 mortahty was complete and the spreading quality of the insecticide 

 was ideal. Other strengths of this solution were tried, and combina- 

 tions of the fish-oil soap with other substances were tested, but noth- 

 ing seemed to be added to the eflS.ciency of the soap through these 

 modifications. 



In addition to the tests discussed in the foregoing paragraphs, we 

 have conducted several large-scale demonstrations in affected cotton 

 fields. The sprays used in these operations were either potassium 

 sulphid. or lime-sulphur, and a barrel pump mounted on some type 

 of horse-drawn vehicle was used for applying the material. 



It should be noted that all tests with sprays were conducted during 

 hot, sunny days in the South. This is important to consider in rela- 

 tion to results, since it is becoming known that similar sprays often 

 yield very different results when appHed mider diverse climatic 

 conditions. 



SPRAYING OUTFITS. 



The sort of outfit to be used for red-spider spraying * depends 

 mainly upon the extent of the occurrence. Many prefer to use a 

 75-cent tin atomizer when only a score or so of plants are to be treated. 

 This instrument is very economical of liquid and throws a fine, vapory 

 spray which penetrates and blows to all accessible parts, but it is not 

 economical of time, and should be employed only where a quart or 

 two of spray material will complete the job. The bucket pump and 

 knapsack pump (fig. 20, p. 58) come into use in cases of considerable 

 scattered infestation or for treatment of a few plants in tall cotton 

 where the platform pump would be impractical. The most economi- 

 cal outfit for a severe case involving several acres consists of a barrel 



1 Our recommendations regarding spraying methods apply primarily to cotton. 



