9 



interchangeable. At any rate, when a tree is affected on the root it will 

 sooner or later be affected above ground. 



Remedies for the Root Form. — Liberal dressing of ashes has a tendency of 

 discouraging the aphis, especially in moist localities, where heavy dews often 

 moisten the ground. 



Gaslime. — About one and a half to two shovelfuls placed around each 

 tree in such a manner that it will not come in direct contact with the bark 

 of the tree, is one of the best remedies. Add to this wood ashes placed 

 directly around the base of the tree to the depth of one inch. Thus the 

 migration to the upper part of the tree can be prevented. 



Remedy Against the Branch Form. — For the treatment, of small trees 

 aflFected brushing with a rosin solution is the best; by diluting it suffi- 

 ciently it can be sprayed on larger trees, and if thoroughly done it is the 

 most effective wash I know of, being harmless to the tree. 



In many instances the lady-bugs are so numerous that the aphis gain 

 but little headway. Lady-bugs should always be protected, and persons 

 ought to make themselves familiar with all their stages. (See chapter on 

 Beneficial Insects.) 



Rosin Solution. — One pound concentrated lye; four pounds rosin. Dis- 

 solve the lye in two quarts of water. Add the rosin; heat until dissolved 

 and add two and a half gallons of water. Use one quart of the solution 

 to the gallon of water. Use at a temperature of 100° F. This solution is 

 well adapted to all kinds of trees affected with aphis. 



RESISTANT STOCK. 



Apple trees with very tough and wiry roots are but little afltected by the 

 woolly aphis, and some varieties exist that are altogether exempt. At the 

 University grounds in Berkeley are two trees originally donated by the 

 well known nurseryman, J. Rock. These trees, after five years' exposure 

 in the midst of a l^adly affected orchard, have remained exempt. Such 

 varieties must be propagated by root-grafting. No doubt other varieties 

 are almosfas good. The seedlings of Rawle's Janet and American Russet 

 are considered resistant, and I believe those of Smith's Cider will likewise 

 prove so. In Australia the Northern Spy bears the reputation of being 

 exempt. 



HONEY DEW 



The presence of all aphis is always accompanied by a sticky, viscid 

 solution on the leaves, which is an excretion from the body of the aphis. 

 Invariably where this is found ants make their appearance, and the ever 

 present connection of aphis with ants is a most remarkable fact. 



Not alone do ants naturally follow the aphis, but certain species have 

 been known to care for their eggs and colonize them on roots in their under- 

 ground galleries, and I have myself seen ants in regular procession carry 

 aphis from the top of a walnut tree down to the ground. The ants greedily 

 lick up the honey dew, and if not excreted fast enough, they will hasten it 

 by pricking the aphis with their antennae. 



Another significant fact connected with aphis is the black smut, which is 

 invariably present whenever honey dew from any of the aphis or scale is 

 secreted. This is a true fungus (Fumago salicina) , Hying on this honey 

 dew alone and not penetrating into the plant. If the aphis is removed, 

 the smut will invariably cease to grow. 

 2^ 



