574 STATE BOARD OF AGRICULTURE. 



very inferior to dust, for the reason that the coarse particles require a» 

 good deal of time for the nicotine to leach out, preventing a thorough, 

 drenching of the roots with nicotine water all at once, as is the case 

 where fine dust is used. The slower action of the coarse tobacco kills 

 some lice to be sure, but much of the nicotine decomposes before it is- 

 extracted and the soil water never becomes strongl} 7 laden with the 

 poison. The soil over the roots should be removed to the depth of 

 several inches and the dust dug in about the roots, after which the soil 

 should be replaced; or a trench may be dug around the tree at a dis- 

 tance of about two feet and then covered again after a liberal supply of 

 the tobacco-dust has been put in. If possible this work should be done 

 before a rain, but a thorough artificial drenching will answer the pur- 

 pose. Tobacco-dust should cost one or two cents a pound, and it is worth 

 that much as a fertilizer even if it were of no value on account of its 

 insecticidal powers. 



Another remedy said to be very useful is kainit. Prof. J. B. Smith of 

 the New Jersey Experiment Station recommends it very strongly.* 

 Kainit is a potash salt which is very efficient as a fertilizer. It should; 

 be used at the rate of about ten pounds to a five or six-year tree and may 

 be spread on the surface of the ground over an area about as large as the 

 roots are supposed to cover, care being taken not to let it come in con- 

 tact with the crown, or in fact within several inches of it. Wood ashes- 

 used in the same way may also prove efficacious. 



All stock purchased from places where this aphis is found should be 

 carefully treated to destroy any lice or eggs that may cling to the roots. 

 Strong tobacco-water is a safe and effective wash for this purpose. 

 Whale-oil soap, using one pound of the soap to six gallons of water, will 

 no doubt prove a useful and effective remedy. Hot water at 130° Fah. 

 will also kill the lice without injury to the stock, if not immersed too 

 long. 



THE WOOLY APHIS OF THE APPLE. 



( Sch izoneura lanigera . ) 



Ranking about equal to the black peach-aphis is the wooly aphis of 

 the apple. Both of these insects have root-inhabiting forms, which ren- 

 ders their extermination very much more difficult than in the case of 

 species living only above ground. The wooly aphis takes its name from 

 the secretion of wool-like flocculent matter covering its body. This 

 wooly covering renders the lice very conspicuous when clustered on the 

 branches of a young apple-tree. Large, knotty swellings are produced on 

 the branches where the lice congregate, and smaller knots and swellings 

 are produced in the same way on the roots (Fig. 6, a). The most serious 

 injury from these wooly-lice is done to young stock, but larger trees suffer 

 as well. When numerous on the roots, the latter become deformed and 

 after a time rot, leaving the plant seriously handicapped for want of suffi- 

 cient food and support. This fact makes itself apparent by the general 

 appearance of the tree, which becomes sickly and may die finally. The- 



♦Economic Entomology, p. 131. 



