364 Fruit-growing in Arid Regions 



Woolly Apple Aphis (Schizoneura lanigera). This is probably 

 the most serious apple pest in this region. It is a bark feeder, 

 and it attacks the roots, the trunk, and the limbs, but does not 

 feed on the fruit or foliage to any extent. This louse is readily 

 recognized on account of its being covered with a white, woolly 

 secretion which has suggested its common name. Upon the 

 trunk and the branches the lice attack either the tender bark 

 about the scars or the bark of tender new shoots. Below ground 

 the lice attack the bark of roots, particularly of the smaller roots, 

 causing warty swellings upon them. If very abundant, the roots 

 are often completely covered with these smooth wart-like growths, 

 which sometimes cause the roots to die and rot off. When very 

 abundant on the rapidly growing twigs, these lice often produce 

 abrupt swellings due to the thickening of the inner bark. Some- 

 times these swollen parts crack open lengthwise, and the limbs 

 may be sufficiently injured to cause them to die. Severest injury 

 is done to the tops, where there is the tenderest and most rapid 

 growth, as in grafts and watersprouts. 



The life habits of this insect may be briefly stated as follows: 

 Early in spring there will be a few living lice in protected places 

 beneath the bark or under the dead bodies of the lice that were 

 killed the previous fall. There will also be a large number of 

 lice living over on the roots beneath the surface of the ground. 

 The lice that live over on top are all very small. Those living 

 over on the roots are of all sizes from the smallest to those that 

 are fully grown. By the time the buds begin to open, the lice 

 that live over on the top will locate on tender new bark and in- 

 sert their beaks and begin to suck the sap of the tree and to grow 

 in size. At the same time a greater or lesser number of small 

 lice that live over winter about the crown of the trees, and per- 

 haps some that came up from the roots, migrate to the top and 

 begin to feed and grow. These lice start the round of develop- 

 ment for the year on the tree-tops. They are usually first de- 

 tected by the fruit-grower when the little lice have grown enough 

 to secrete a white covering to their bodies which makes them 

 appear like little moldy spots upon the bark. These lice in- 

 crease very rapidly, so that by the middle of June or first of July 



