60 BULLETIN 416, U. S. DEPARTMENT OF AGRICULTURE. 
eign vegetation remained free of red spiders, while the neglected | 
portion eeioped serious infestation. Too much emphasis can not | 
be placed on the importance of ridding all field borders, ditch banks, | | 
terraces, etc., of all vegetation so far as possible. Pokeweed and 
other persistent perennials should be grubbed out. i 
The destruction of weeds by spraying with sodium arsenite at the | 
rate of 1 pound to 20 gallons of water is very effective. vy 
Many cases of teers in urban localities can be traced back to 
borders of cultivated violets growing in near-by house yards. (Pe 
VII.) In several instances of past severe annual infestation violets _ 
adjoining fields have been thoroughly sprayed, with the result that | 
no red spiders appeared in these fields. The objection to this treat- | 
ment is the failure on the part of the average person to persevere 
with the spraying until the mites have been entirely exterminated. 
The most satisfactory procedure consists in the removal and destruc- | 
tion of the violets. K 
Karly in the investigation it appeared possible that there might 
be a variation in the degree of susceptibility of cotton varieties to the — 
ced spider, for in 1903 Watt and Mann stated that there was a marked 
difference in the susceptibility of tea (Thea) varieties in India to 
the Indian red spider, Tetranychus bioculatus Green. 
During 1912, 1913, and 1914 many varieties of cotton have been 3 
planted in exposed fields and records have been made of the per- 
centage of infestation developing in each. Paralleling these experi- 
ments data have also been gathered from many cases of infestation in 
South Carolina and North Carolina. In Table X XVII, which repre- 
sents the relative degree of infestation of the varieties tested at 
Batesburg, the position of each variety is obtained by averaging the | 
infestation percentage as exhibited by it during the several years; thus, 
variety No. 1 was the heaviest infested and No. 37 was the lightest. 
iI 
{ 
Taste XXVI.—List of standard varieties of cotton, tested for susceptibility to red-spider 
injury. Batesburg, S.C. 
1. Lone Star. 20. Dixie. 
2. Keenan. 21. Cleveland. 
3. Christopher. | 22. World’s Wonder. 
4. Bank Account. | 23. Russell Big Boll. 
5. Rublee. | 24. Hite’s Prolific. 
6. Money Maker. 25. Bostwick. 
7. Cook’s Improved. 26. King. 
8. Simpkins. | 27. Columbia L. S.. 
9. Uncle Sam. | 28. Poor Land. 
10. Broadwell. | 29. Bates. 
11. Stone’s. | 30. Rowden. 
12. Toole. (eats rt: 
13. Covington-Toole. 32) Emcee: 
14. Hawkins. | 33. Shine’s Early. 
15. Mebane Triumph. | 34. Sea Island. 
16. Lowe. | 35. Wade’s Triumph. 
17. Culpepper. | 36. Dongola. 
18. Peterkin. | 37. Summerour’s Half and Half. 
19. Excelsior. 
