189 



and paraffin oil emulsion, using a spray gun with a pressure of from 

 225 to 250 pounds. In each case the spray was directed towards 

 the lower surface of the leaves. Lime-sulphur applied in December 

 at the rate of 1 gal. to 40 of water and again in March at the 

 rate of 1-50 killed about 50 per cent, of the scales ; caustic 

 potash fish-oil soap, applied at same time and interval at the rate 

 of 20 lb. to 25 U.S. gals, water killed about 80 per cent., slight injury 

 being noticed after each spraying, especially on the sunny side of the 

 trees ; neither of these spraj's removed sooty mould. Various miscible 

 oils applied in December at a strength of 1 gal. to 70 of water and 

 again in March at a strength of 1-80 also killed about 80 per cent, 

 of the scales. Some of the oils contain harmful ingredients causing 

 injury to the foliage, and they do not spread as effectively as oil 

 emulsions. Paraffin oil emulsion applied in December at the rate 

 of 1 gal. stock solution to 70 of water and in March at 1-80 killed 

 from 90 to 95 per cent, of the scales. The use of hard water with oil 

 emulsions causes separation of the oil, resulting in severe injury to the 

 foliage ; this may be avoided by the addition of 4-5 lb. of caustic 

 fish-oil soap to every 125 U.S. gals, of hard water. 



Some emulsions, however, have a proper stabiliser incorporated 

 with them in the course of manufacture. The results obtained depend, 

 to a considerable extent, on the thoroughness of the application. 



Morrill (A. W.). Arizona Wild Cotton or Thurberia and its Insect 

 Enemies in Relation to the Cotton Industry of the Southwest. 



— //. Econ. Ent., Geneva, A^ 1'., xiv, no. 6, December 1921, 

 pp. 472-478. 



Experience with the cotton boll-weevil [AntJionomus grandis] 

 shows that the maintenance of narrow non-cotton zones as suggested 

 by the Arizona officials [R.A.E., A, ix, 341-342] does not stop the 

 progress of the weevil, as this pest will cross a five- or ten-mile non- 

 cotton zone faster than if it were planted entirely with cotton. 

 The relationship between weevil and food-plant having been disturbed, 

 the outlawed cotton plantings become valuable as trap crops. In the 

 circumstances the more cotton grown in the prohibited area the better 

 would be the protection of the more important cotton sections within 

 range of the two pests here dealt with, A. grandis thurberiae, Pierce, and 

 Thurberiphaga catalina, Dyar (thurberia bollworm). Under natural 

 conditions the relation of the food-supply to the former in its native 

 habitat was such that unless the insects or the native food-plants were 

 disturbed there was little danger of the infestation spreading to culti- 

 vated cotton in the valleys except through transportation by means of 

 floods from the mountains. The campaign directed against the plant 

 rather than its insect enemies made the infestation of the cultivated 

 cotton by ffight almost inevitable, as was subsequently proved by the 

 infestation of the cotton fields by A. grandis thurberiae in 1920. 



The existence of T. catalina in the same localities as A. grandis 

 thurberiae must be taken into consideration in any attempt to eradicate 

 the weevil and its food-plant in any area. The proper methods of 

 dealing with the wild cotton problem in Arizona will be discussed 

 elsewhere, the object of this paper being rather to point out the 

 danger of political interference in matters that properly belong to 

 the field of economic entomology. 



