SoMK Important Orchard Plant Lick 15 



determined on the assumption that only that percentage of the 

 total number would hatch which did hatch in the lots laid aside 

 as checks and not treated with an\" suljstance in an)- wa}'. 



Table I 



EFFECT OF SPRAYS ON APHIS EGGS 



PrufDrfioii Kill.'d 



Materials Used Per cent 



Lime-sulfur, i-8 or 1-9 85-100 



Lime-sulfur, 1-8 plus "Black Leaf 40," 1-500 97 



''Black Leaf 40," 1-500 plus laundry soap, 2 Ih. to 50 gal. . . 45 



Laundry Soap, "Fels Naptha," j lb. to 50 gal 5-33 



"Scalecide." 1-15 25-65 



*'Mechling's Sca!e Oil,'' 1-19 79-90 



Sodium Sulfocarbonate. 1-19 85 



Sodium Chloride, i gm.* to 5 cc.** water 26-35 



Sodium PLvdrnxide, 2 pt. to 98 cc. water 85-95 



Crude Carbolic Acid (100%), 2 cc. to 98 cc. of solution, 



plus soap, 2 \h. to 50 gal. water 93-100 



* gm. — gram. 

 ** cc. — culjic centimeters. 



Several important facts stand out in this table. The deadly 

 quality of lime-sulfur is increased by the addition of 40 per cent 

 nicotine. "Scalecide" is much less effective than lime-sulfur 

 alone. "Scalecide," in which we are assured there is no car- 

 bolic acid, is much less effective than "Mechling's Scale Oil," 

 in which, according- to the makers, is found a percentage of 

 carbolic acid. The great efficiency of a 2 per cent crude car- 

 bolic acid solution to Avhich soap has been added is shown. 



In the present stage of knowledge none of the su])stai:ces can 

 be recommended for the destruction of the eggs during dor- 

 mancy, but the prospects for the development of such a s]>ra\- 

 seem encouraging. It can be said, however, that the studx- 

 points to the idea that an application of the lime-sulfur ar.d 

 tobacco mixture at the green bud stage, even if not all of the 

 eggs have hatched, is likely to give control l)y reason of the 

 destruction of the unhatched eggs as well as the newly-hatched 

 nymphs. 



Destroying the Aj^liis in the Sf'i'ing ami Si 



ininier 



In the spring, when first hatched, the }()img nvmphs are \-erv 

 delicate, and, consequently, very susceptible to the effect of 

 spraying mixtures. This led investig^ators to place reliance on 

 spring and summer spraying as a means of controlling the 



