INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 71 



from the crown. Use two or three gallons of liquid per tree, spray- 

 ing thoroughly on the exposed roots. When the liquid is nearly all 

 soaked into the soil cover up the basin. The materials which have 

 given the most satisfaction follow : 



Tobacco Leaves. — Place in the bottom of the excavation dry tobacco 

 ieaves to the depth of one half or one inch and replace the soil. The 

 action of the moisture on the tobacco will carry the nicotine thus 

 extracted to the lice and kill a great many if not all. The use of 

 tobacco leaves in this manner does not injure the trees. 



Tobacco Decoctions. — The floor of the excavation may be thoroughly 

 sprayed with a very liberal application of a tobacco decoction com- 

 posed of one part "black leaf 40" (40 per cent nicotine sulphate). 



Carbon Bisulfid. — In light sandy, but not too porous soils, carbon 

 bisulfid is used very effectively. The treatment should be made 

 early in the spring, about April, as follows : make four or five holes 

 eight inches deep in a radius of eighteen inches or two feet from the 

 tree. Into each pour from 3 to 4 liquid ounces of carbon bisulfid, 

 and immediately cover the hole. See that the liquid does not come 

 in contact with the roots, as it is likely to kill them. 



Tanglefoot Bands.- — If the dormant trees are sprayed with a strong 

 solution of kerosene emulsion or lime-sulphur just before the buds 

 open in the spring, it is well to put a tanglefoot band around the 

 trunks to keep root forms from migrating to the tops. 



METHODS FOR CONTROLLING THE AERIAL FORMS 



The sprays used in controlling the aerial forms (those infesting the 

 bark, fruit and foliage) may be arranged under the two following 

 heads — winter sprays and summer sprays: 



Winter Sprays. — In order to destroy the wintering eggs deposited 

 upon the branches in the fall by the sexual females it is necessary 

 to apply strong sprays during the winter from November to March 

 when the trees are dormant and able to stand such solutions. By 

 killing the eggs the next season's broods may be greatly reduced. 

 For this purpose the miscible oils 42 and oil emulsions are specially 

 adapted and give best results. The spraying must be thoroughly done 

 in order to completely drench the tops and tips of outside twigs which 

 are favorite places for egg-laying. 



Summer Sprays. — During the summer, when the trees are in foliage, 

 much weaker sprays must be used to avoid burnings. Various 

 formulae of nicotine and tobacco sprays appear to be most satisfac- 

 tory. The two following formulae are specially recommended : 



A. 43 Black leaf 40 (nicotine sulphate) £ ounce 



Soap 4 ounces 



Water . 4 gallons 



Dissolve the soap in hot or boiling water; add the "black leaf 40" 

 and boil for a few minutes, after which add enough water to make 

 four gallons of prepared material. 



42 The formulas for all sprays are given In the chapter on sprays near the back of 

 the book. 



"Parker, J. R., Cir. No. 28, Mont. Agrcl. Exp. Sta., 191.3, 



