i6 



Bulletin 328 



species. Unfortunately, several years of experience have demon- 

 strated for the rosy louse, at least, that an attempt to control it 

 after the foliage has been curled is sure to fail, and that an 

 attempt to control it after the buds have reall_\- opened is almost 

 certain to fail. The period in the spring when all three species 

 can be brought under control has been thought to be very short, 

 and was thought to extend from the hatching of the egg to the 

 opening of the buds. The problem was further complicated by 

 the fact that the eggs of the rosy aphis hatched, in some cases, 

 coincidently with the opening of the early buds. 



Table 2 

 effect of nicotine sprays on rosy aphis 



'Black Leaf 40" (i part) + water (goo I arts) 



'Black Leaf 40"' (i part) + water (500 parts) I 

 + soap (2 His. to 50 gal.) ! 



In 191 5 Parrott and Hodgkiss^ recommended the delay of the 

 usual winter-strength lime-sulfur, to which 40 per cent nicotine 

 has been added at the rate of ;>4 of a pint to 100 gallons, or 

 about I part of nicotine to 1,000 parts of the spraying mixture, 

 and the application of the mixture at the green bud stage. In 

 1915 one of our best apple growers almost completely failed to 

 obtain control of aphis by adding nicotine to his pink-bud or 

 cluster-cup sprav at the rate of i to 800, while another claimed 

 perfect control by adding the 40 per cent nicotine to the same 

 spray at the rate of i to 500. To discover the strength of nico- 

 tine necessary for a complete kill of all ages of the rosy ai)his, 

 which has seemed more resistant to spraying solutions than 

 either of the others, the experiment recorded in table 2 was made. 



* Parrott, P. J., and ilodgkiss, H. E., igi5. Controlling plant lice in aiiple 

 orchards. N. Y. {(icneva) .\gr. Exp. Sta. Bnl. 402. 



